INTERNATIONAL  ATOMIC  WEIGHTS 
FOR   1913* 
0  =  16 


Name. 

Symbol. 

Atomic 
Weight. 

Name. 

Symbol. 

Atomic 
Weight. 

Aluminium  
Antimony 

Al 

Sb 

27.1 

120  2 

Molybdenum.  .<S.  . 
Neodymium    .... 

Mo 
Nd 

96.0 
144  3 

A 

39  88 

Neon 

Ne 

20  2 

«.lgUll.    .    ...... 

Arsenic  .  k^.  .... 

As 

74.96 

Nickel  if,  .  . 

Ni 

58.68 

Barium       

Ba 

137.37 

Niton 

Nt 

222  4 

Bismuth      ^ 

Bi 

208  0 

Nitrogen  

N 

14.01 

Boron          

B 

11.0 

Osmium  

Os 

190.9 

Bromine            .  .  • 

Br 

79  92 

Oxygren  .  . 

O 

16  00 

Cadmium    ^ 

Cd 

112  40 

Palladium 

Pd 

106  7 

Caesium 

Cs 

132  81 

Phosphorus.        .  . 

P 

31.04 

C&lcium 

Ca 

40  07 

Platinum 

Pt 

195  2 

Carbon 

c 

12  00 

Potassium  

•rr 

39.10 

Cerium      

Ce 

140.25 

Praseodymium.  .  . 

Pr 

140.6 

Chlorine        .    .  .  • 

Cl 

35.46 

Radium  

Ra 

226.4 

Chromium 

Cr 

52  0 

Rhodium     

Rh 

102.9 

Cobalt         *<£... 

Co 

58.97 

Rubidium  

Rb 

85.45 

C  o  lumb  ium 

Cb 

93  5 

Ruthenium  .... 

Ru 

101.7 

Coooer           */f. 

Cu 

63.57 

Samarium  

Sm 

150.4 

Dv 

162  5 

Scandium  

Sc 

44.1 

Erbium      

**j 

Er 

167  7 

Selenium  

Se 

79.2 

Eu 

152  0 

Silicon 

Si 

28  3 

Fluorine 

F 

19  0 

Silver        */  

Ag 

107.88 

Gadolinium 

Gd  ' 

157  3 

Sodium  

Na 

23.00 

Gallium      

Ga 

69.9 

Strontium  

Sr 

87.63 

Germanium  

Ge 

72.5 

Sulphur  

S 

32.07 

Glu  cinum 

Gl 

9  1 

Tantalum  

Ta 

181  5 

Gold       

Au 

197.2 

Tellurium  

Te 

127.5 

Helium 

He 

3  99 

Terbium  

Tb 

159  2 

Ho 

1  AQ     X 

Thallium     

Tl 

204.0 

H 

1  008 

Thorium 

Th 

232  4 

Indium      

In 

114  8 

Thulium  

Tm 

168.5 

Iodine 

I 

126  92 

Tin  •  

Sn 

119.0 

Iridium   

Ir 

193.1 

Titanium  

Ti 

48.1 

Fe 

55  84 

Tungsten 

W 

184  0 

Krypton 

Kr 

82  92 

Uranium     

u 

238.5 

La 

139  0 

Vanadium  ' 

v 

51  0 

Lead              S 

Pb 

207  10 

Xenon  

Xe 

130.2 

Lithium 

Li 

6  Q4 

Ytterbium 

Yb 

172.0 

Lutecium  

Lu 

174.0 

(Neoytterbium) 

Magnesium. 

Me1 

24  32 

Yttrium         

Yt 

89.0 

Manganese  .  .*^.  . 

A«.g 

Mn 

54.93 

Zinc  K\  .  .  . 

Zn 

65.37 

Mercury  k  .  . 

Hg 

200.6 

Zirconium  

Zr 

90.6 

*  Compiled  by   the    International  Committee  on  Atomic  Weights  con- 
sisting of  F.  W.  Clarke,  W.  Ostwald,  T.  E.  Thorpe,  and  G.  Urbain. 


LIBRARY 

I    UNIVERSITY  OF 
\CALIFORNIA 


METHODS 

IN" 

METALLURGICAL  ANALYSIS 


BY 


CHARLES  H.  WHITE 

Assistant  Professor  of  Mining  and  Metallurgy  in  Harvard  University 
and  in  the  Massachusetts  Institute  of  Technology 


1O6  ILLUSTRATIONS 


NEW  YORK 

D.  VAN  NOSTRAND  COMPANY 

25  PARK  PLACE 

1915 


••  !      : 


Copyright,  1915 

BY 

D.  VAN  NOSTRAND  COMPANY 


THE  SCIENTIFIC  PRESS 
BROOKLYN.  N.  Y. 


PREFACE 


IN  this  volume  are  brought  together  those  methods  in 
metallurgical  analysis  which,  owing  to  their  fitness,  seem  to  have 
been  most  generally  adopted  in  American  metallurgical  lab- 
oratories. The  procedures  are  given  for  the  sake  of  clearness 
in  as  direct  statement  as  possible,  without  regard  to  literary 
style. 

Explanatory  notes  have  been  introduced  where  they  are 
most  needed  by  the  beginner,  but  are  so  subdued  as  not  to  annoy 
the  experienced  reader  who  may  wish  to  omit  them. 

From  several  years'  experience  I  find  that  students  who 
have  had  adequate  preparation  in  qualitative  analysis  can  take 
up  metallurgical  analysis  at  once  without  having  previously 
taken  a  general  course  in  quantitative  analysis.  For  the  benefit 
of  such  students  the  various  operations  in  both  gravimetric  and 
volumetric  analysis  are .  described  in  detail  at  the  beginning  of 
the  book,  and  the  methods  that  such  students  would  ordinarily 
take  up  first  are  given  in  greater  detail  than  those  which  are 
usually  assigned  after  considerable  experience  has  been  gained. 

For  more  details  than  it  is  possible  to  give  in  a  work  of  this 
kind,  the  reader  should  consult  the  references  given  in  the  foot- 
notes, and  in  the  bibliography  on  page  335. 

In  addition  to  those  whose  names  are  mentioned  hereafter 
in  these  pages,  I  am  indebted  to  my  colleagues;  Professor  Albert 
Sauveur  for  many  helpful  suggestions,  especially  for  the  im- 
provement of  the  chapter  on  Iron  and  Steel,  and  Professor  G. 
S.  Raymer  for  valuable  criticism  of  the  chapters  on  Sampling 

iii 

819524 


iv  PREFACE 

and  Fire  Assaying.  I  have  also  received  generous  assistance 
in  collecting  material  and  in  preparing  the  illustrations  from 
Mr.  W.  S.  Weeks,  Instructor;  and  Messrs.  F.  C.  Langenberg 
and  R.  S.  Cochran,  Assistants,  in  the  Harvard  Mining  School. 

C.  H.  W. 

HARVARD  UNIVERSITY, 
CAMBRIDGE,  MASS., 
Jan.  2,  1915. 


TABLE  OF  CONTENTS 


PAGE 

Definition  of  the  Subject 1 

Purposes  for  which  Analyses  are  Made 1 

Selection  of  Methods 1 

Equipment  of  the  Laboratory 5 

Sampling — Necessity  of  Correct  Sampling 8 

Classification  of  Materials 8 

General  Principles  of  Sampling 8 

The  Operations  of  Analysis — Gravimetric 15 

Weighing 15 

Care  and  Use  of  the  Balance 15 

The  Weights 16 

The  Operation  of  Weighing 16 

Precautions  in  Weighing 18 

Weighing  for  Analysis 18 

Dissolving 18 

Reagents 19 

Precipitation 20 

Filtration 21 

Use  of  the  Gooch  Crucible 25 

Washing  Precipitates 26 

Burning  Precipitates 27 

The  Care  of  Platinum 29 

To  Clean  Platinum 29 

The  Desiccator 30 

Weighing  Precipitates 30 

Calculation  of  Results 31 

Factor  Weights 32 

Volumetric  Analysis 33 

Volumetric  Apparatus 33 

Cleaning  Solution 35 

Titration 35 

Standard  Solutions 36 

v 


Vl  TABLE  OF  CONTENTS 

PAGE 

Volumetric  Analysis — Normal  Solutions 36 

Empirical  Standard  Solutions 37 

Preparation  of  an  Empirica  IStandard  Solution 37 

Standardizing  Solutions 38 

Correcting  a  Standard  Solution 39 

Factor  Weights  for  Standard  Solutions 40 

Indicators 41 

Colorimetry 42 

Methods  of  Analysis  in  the  Metallurgy  of  Iron  and  Steel 45 

Methods  for  Ores 45 

Sampling  Iron-ore 45 

Sampling  Ore  in  Cars 45 

Moisture  Sample 47 

Sampling  a  Cargo „ 47 

Preparation  of  the  Sample 48 

Moisture 48 

Hygroscopic  Water 49 

Combined  Water 49 

Loss  on  Ignition 50 

Iron  in  Ores 50 

Potassium  Permanganate  Method 50 

Standardization  of  Permanganate  Solution ; 51 

Iron  in  Ferrous  Ammonium  Sulphate — Gravimetric  Method 52 

Potassium  Bichromate  Method  for  Iron  in  Ore 62 

Determination  of  Ferrous  Iron 64 

Free  Metallic  Iron 66 

Silica  in  Ore 69 

Sulphur  in  Ore 73 

Phosphorus  in  Ore 75 

Alumina  in  Ore 87 

Manganese  in  Ore 88 

Lime  in  Ore 96 

Magnesia  in  Ore 97 

Titanium  in  Ore 98 

Analysis  of  Iron  and  Steel 103 

Sampling 103 

Detection  of  Segregations  of  Sulphur 104 

Silicon  in  Iron  and  Steel 105 

Silicon  in  Ferro-Silicon 107 

Sulphur  in  Iron  and  Steel 108 


TABLE  OF  CONTENTS  vii 

PAGE 

Analysis  of  Iron  and  Steel — Carbon  in  Iron  and  Steel 115 

Phosphorus  in  Iron  and  Steel 129 

Manganese  in  Iron  and  Steel 132 

Manganese  in  Ferro-Manganese  and  Spiegel 133 

Titanium  in  Iron  and  Steel 135 

Nickel  in  Steel 137 

Chromium  and  Vanadium  in  Steel 141 

Tungsten  in  Steel 146 

Molybdenum  in  Steel 148 

Molybdenum  in  Molybdenum  Powders 149 

Copper  in  Steel 150 

Nitrogen  in  Steel 151 

Hydrogen  in  Steel 153 

Oxygen  in  Steel 155 

Analysis  of  Iron  Slags 157 

Analysis  of  Limestone 160 

Methods  of  Analysis  in  the  Metallurgy  of  Copper,  Lead,  etc 168 

Copper  in  Ore 168 

Lead  in  Ore 175 

Zinc  in  Ore 178 

Arsenic  in  Ore 180 

Analysis  of  Copper  Matte 184 

Analysis  of  Chilled  Blast  Furnace  Slags 188 

Analysis  of  Reverberatory  Slag 195 

Analysis  of  Briquettes  and  Other  Copper-bearing  Products 196 

Analysis  of  Copper  Bullion 197 

Analysis  of  Alloys * 210 

Brass  and  Bronze 210 

White    Alloys    Containing  Tin,    Lead,    Copper,    Phosphorus,    and 

Antimony 213 

Alloy  Containing  Tin,  Copper,  Antimony,  Lead,  and  Zinc 215 

Bismuth  in  Alloys -. 218 

Analysis  of  Copper  Containing  Lead,  Antimony,  Arsenic,  Iron,  Cobalt, 

Nickel,  when  only  a  small  Sample  of  the  Material  is  Available 220 

Methods  of  Analysis  in  the  Production  of  the  Precious  Metals 224 

Fire  Assaying 224 

Assay  of  Gold  and  Silver  Ores ' 224 

Assay  of  Bullion 235 

Gold  and  Silver  in  Lead  Bullion 241 

Gold  and  Silver  in  Cyanide  Solutions .  ,  242 


viii  TABLE  OF  CONTENTS 

PAGE 

Methods  of  Analysis  in  the  Production  of  the  Precious  Metals — Prepara- 
tion of  Pure  Silver. 242 

Preparation  of  Pure  Gold 242 

Testing  Cyanide  Solutions 243 

Cyanogen  in  Commercial  Cyanide 247 

Weight  of  Ore  in  Slime 248 

The  Platinum  Metals 249 

Analysis  of  Fluxes 253 

Analysis  of  Fuels 253 

Coal 253 

Proximate  Analysis  of  Coal 254 

Sulphur  in  Coal 256 

Ultimate  Analysis  of  Coal 259 

Calorific  Power  of  Coal 260 

Petroleum 271 

Fractional  Distillation  of  Crude  Petroleum 272 

Sulphur  in  Petroleum 272 

Calorific  Power  of  Liquid  Fuels 272 

Water  in  Oil 273 

Gas  Analysis 273 

Calorific  Power  of  Gas 283 

Analysis  of  Clay 286 

Methods  for  the  Determination  of  Some  of  the  Minor  Metals 290 

Chromium 290 

Nickel  and  Cobalt 290 

Cadmium 292 

Mercury 293 

Tin 294 

Tungsten 296 

Vanadium 297 

Uranium 298 

Methods  for  the  Determination  of  Some  of  the  Rarer  Metals 299 

Lithium 299 

Strontium 300 

Barium 301 

Columbium  and  Tantalum 301 

Caesium ." 302 

Germanium ; 302 

Glucinum 303 

Thallium.  .  .  303 


TABLE  OF  CONTENTS  ix 


Methods  for  the  Determination  of  Some  of  the  Rarer  Metals — Cerium . .  304 

Thorium 304 

Yttrium 305 

Zirconium 306 

Testing  Lubricating  Oil 307 

Examination  of  Boiler  Water 308 

Detection  of  the  Metals 314 

Tables 324 

The  Elements;   their  Atomic  Weights,  Melting-points,  Boiling-points, 

and  Densities 324 

Factors " 327 

Table  of  Logarithms 328 

Gas  Table 330 

Density  Table  for  Hydrochloric  Acid 332 

Density  Table  for  Sulphuric  Acid 333 

Density  Table  for  Nitric  Acid 334 

General  References 335 

Index 339 

Table  of  Atomic  Weights Inside  of  front  cover 

Table  of  Equivalent  Weights Inside  of  back  cover 


METALLURGICAL  ANALYSIS 


Definition.  Metallurgical  Analysis  is  the  application  of 
analytical-chemical  methods  to  the  chemical  problems  of 
metallurgy,  including  problems  of  valuation  and  utilization  as 
well  as  of  production. 

Purposes  for  which  Analyses  are  Made.  The  analysis  of  any 
metallurgical  material  or  product  is  made  for  one  or  more  of  the 
following  reasons:  (1)  As  a  basis  for  the  estimation  of  its  com- 
mercial value,  (2)  to  determine  its  fitness  or  adaptability  to  a 
certain  use,  or  (3)  as  a  guide  in  the  operation  of  a  process  or  in 
determining  the  efficiency  of  a  process  or  treatment. 

Selection  of  Methods.  It  is  obvious  from  the  above  classifica- 
tion that  analyses  are  made  either  for  technical  purposes  or 
for  commercial  purposes.  For  example,  the  slag  from  a  blast 
furnace  is  analyzed  to  determine  if  the  furnace  charge  is  correct. 
In  the  open-hearth  process  of  steel  making,  frequent  determina- 
tions of  carbon  are  made  that  the  heat  may  be  terminated  when 
the  carbon  has  been  reduced  to  the  desired  point.  These  deter- 
minations are  for  technical  purposes,  and,  while  accurate  results 
are  desirable,  the  important  requisite  is,  that  the  results  be 
obtained  within  a  specified  time,  even  if  the  highest  degree  of 
accuracy  must  thereby  be  sacrificed;  for  it  is  of  no  special  value 
to  the  metallurgist  to  learn  the  composition  of  the  slag  after 
the  whole  lot  of  ore  has  been  charged  into  the  furnace;  nor  can 
the  steel  maker  use  the  carbon  determinations  if  they  are  not 
given  to  him  within  a  few  minutes  after  the  samples  of  molten 
steel  are  taken  from  the  furnace, 


METALLURGICAL  ANALYSIS 


SELECTION  OF  METHODS 

On  the  other  hand,  buyers  and  sellers  of  blister  copper  must 
know  very  exactly  the  percentage  of  copper  as  well  as  the  amounts 
of  the  precious  metals  present,  in  order  to  fix  a  just  price  for  the 
bullion.  In  making  determinations  for  commercial  purposes, 


PLAN 


FIG.  2. — Details  of  Equipment  of  a  Working  Table. 

especially  in  cases  where  large  sums  of  money  are  involved, 
the  most  accurate  methods  known  must  be  applied,  and  should 
be  carried  out  by  the  most  skilled  analysts. 

The  metallurgical  chemist  should  ordinarily  select,  for  any 
particular  determination,  the  method  by  which  he  can  obtain 


METALLURGICAL  ANALYSIS 


LABORATORY  EQUIPMENT  5 

the  most  accurate  result  in  the  time  allowed;  but  in  cases  where 
only  approximations  to  a  fair  degree  of  accuracy  are  demanded, 
methods  will  be  selected  that  are  less  expensive  in  time  and 
materials;  for  the  chemical  department  as  well  as  the  other 
departments  of  a  metallurgical  establishment  should  have 
regard  for  economy  of  labor  and  materials. 

Equipment  of  the  Laboratory.  The  laboratory  should  be 
designed  and  constructed  for  the  special  purposes  for  which  it 
is  to  be  used,  and  it  is  economy  to  consider  the  special  fitness 
of  an  apparatus  and  the  possible  efficiency  attainable  by  its 
use,  as  well  as  its  initial  cost. 

Laboratories  for  schools  and  for  general  metallurgical 
analysis  should  have  the  working  tables  fitted  for  the  ordinary 
chemical  operations  of  solution,  evaporation,  filtration,  and 
washing  of  precipitates,  titration,  etc.  At  each  table  there 
should  be  gas,  water,  compressed  air,  suction,  a  hood  with  air- 
bath  and  hot-plate. 

The  hoods  should  be  conveniently  placed  and  well  ventilated. 
They  are  better  made  of  glass  and,  if  flues  for  an  up-draft 
interfere  with  the  light,  the  hoods  should  be  provided  with  a 
down-draft  with  strong  suction.  Such  hoods  are  easily  kept 
clean,  they  do  not  obstruct  the  light,  and  in  their  use  there 
is  no  danger  of  dust  falling  from  the  flue  to  spoil  determina- 
tions. 

A  satisfactory  arrangement  of  these  details  is  shown  in  Figs. 
1,  2  arid  3.*  In  addition  to  the  exhaust  from  the  hoods,  fresh 
filtered  air  should  be  supplied  to  the  laboratory  by  a  plenum 
fan.  The  room  should  be  well  lighted;  for  colorimetry,  light 
from  north  windows  is  best. 

There  should  also  be  sample  grinders,  drills  for  sampling 
metals,  stirrers,  shaking  machines,  centrifugal  machines,  and  an 
electric  current  should  be  available  for  operating  these  machines, 

*  See  "  The  Equipment  of  a  Laboratory  for  Metallurgical  Chemistry 
in  a  Technical  School."  Trans.  Am.  Inst.  of  Mining  Engineers,  35,  117. 


METALLURGICAL  ANALYSIS 


LABORATORY  EQUIPMENT  7 

and  for  heating  combustion  furnaces  and  for  electrolysis.  There 
must  also  be  provided  the  necessary  balances,  a  still  for  pure 
water,  calorimeters,  colorimeters,  and  other  special  appliances 
that  may  be  demanded. 

The  works-laboratory  designed   for    much   routine  analysis 


Skylight 


fftt  ///  rifffi/iiff/rffiri!mffiif/f/rrrifiiiinii[ini//niii  / 

SECTION    ON   A  •  B 


FIG.  5. — Section  through  the  Laboratory  Shown  in  Fig.  4. 


may  have  tables  or  sections  fitted  with  the  necessary  appliances 
and  reagents  for  carrying  out  these  special  operations  or  deter- 
minations with  the  greatest  facility.  Figs.  4  and  5  are  the  plan 
and  section  of  such  a  laboratory,  described  by  Edward  Keller.* 

*  Trans.  Amer.  Inst.  Mining  Engineers,  36,  3 


METALLURGICAL  ANALYSIS 


SAMPLING 

Necessity  of  Correct  Sampling.  By  chemical  analysis  it  is 
only  the  small  portion  of  material  that  is  weighed,  dissolved, 
and  analyzed,  whose  composition  is  determined.  If,  however, 
the  small  portion  analyzed  has  been  taken  from  a  larger  quan- 
tity which  is  uniform  throughout,  then  the  portion  analyzed 
was  a  true  sample  and  the  analysis  indicates  the  composition 
of  the  whole.  It  follows  that  every  determination  to  be 
of  any  value  in  metallurgy  must  consist  of  two  distinct  and  equally 
important  operations.  They  are  sampling  and  chemical  analysis. 

The  object  in  sampling  is  to  separate  from  the  whole  body 
of  the  material  whose  composition  is  desired,  a  small  quantity 
for  analysis  that  shall  have  the  same  composition  as  the  whole; 
for  it  is  obvious,  that  if  the  sample  is  not  representative,  the 
most  accurate  chemical  analysis  cannot  give  the  information 
desired,  that  is,  the  true  composition  of  the  material  in  question. 

The  sampling  of  ore,  or  mineral  in  place,  *  is  not  usually  carried 
out  by  the  chemist,  but  sampling  for  all  other  purposes  for 
which  metallurgical  analyses  are  made  is  done  by  him,  or  under 
his  direction,  and  should  receive  his  careful  consideration. 

Classification  of  Materials.  The  method  of  sampling  will 
depend  upon  the  nature  of  the  material  to  be  sampled.  For 
convenience  in  the  study  of  sampling,  metallurgical  materials 
may  be  divided  into  the  following  classes: 

1.  Fluids  (a)  Liquids — water,  oil,  molten  metals,  slags,  etc. 

(6)  Gases — flue  gas,  producer  gas,  etc. 

2.  Tough  or  sectile  materials — metals,  alloys,  etc. 

3.  Brittle   or  frangible   materials — ores,   fluxes,   coal,   brittle 

metals,  alloys,  etc. 

General  Principles  of  Sampling.  It  is  practically  impossible 
to  take  a  theoretically  perfect  sample  of  ordinary  metallurgical 

*  Those  interested  in  this  subject  will  consult  "  The  Sampling  and 
Estimation  of  Ore  in  a  Mine,"  T.  A.  Rickard. 


SAMPLING  9 

materials,  and  the  degree  of  perfection  to  be  attained  is  usually 
determined  by  the  value  and  uniformity  of  the  material  in 
question;  the  more  uniform  the  material,  the  simpler  and  cheaper 
is  the  work  of  sampling;  and  the  more  uneven  the  mixture,  the 
more  difficult  and  expensive  is  the  operation.  For  example, 
the  smallest  quantity  of  pure  water  that  can  be  taken  is  a  fair 
sample  of  the  whole,  while  on  the  other  hand  it  is  practically 
impossible  to  take  a  satisfactory  sample  of  a  very  "  spotted  " 
gold-ore. 

To  sample  a  fluid  it  is  only  necessary  to  mix  it  thoroughly 
and  withdraw  any  convenient  portion.  The  sampling  of  metals 
and  alloys  after  solidification  is  not  so  easily  effected  as  when 
molten  on  account  of  the  segregation  of  impurities  on  cooling. 
It  is  therefore  necessary  to  take  drillings  from  such  materials  in 
a  systematic  way  and  mix  them  thoroughly  before  taking  out 
the  final  sample.  See  page  197  for  the  sampling  of  blister 
copper. 

The  method  of  sampling  fraymental  materials  like  ore,  coal, 
and  limestone  will  be  given  under  the  analysis  of  each,  and  gen- 
eral principles  only  will  be  considered  here.  The  first  considera- 
tion is  the  quantity  to  be  taken  for  the  original  sample.  This 
will  depend  upon  the  value  and  uniformity  of  the  material  and 
the  size  of  the  largest  particles.  As  has  been  said  already,  if 
the  material  is  uniform  in  composition,  only  a  small  portion  is 
required,  and  this  is  true  regardless  of  the  size  of  the  lumps 
into  which  it  is  broken,  but  ores  that  break  into  lumps  of  great 
variation  in  size,  are  usually  uneven  in  composition;  that  is, 
the  large  pieces  are  probably  very  different  in  composition 
from  the  fine.  If  such  an  ore  is  all  crushed  to  a  fine  powder 
and  thoroughly  mixed,  any  small  portion  may  be  taken  as  a 
correct  sample,  but  if  it  is  not  so  crushed  and  mixed,  the  por- 
tion taken  for  the  sample  must  be  larger,  and  the  quantity  will 
depend  upon  the  size  of  the  largest  particles  of  the  material. 

In  problems  of  sampling  there  are  so  many  unknown  quan- 


10  METALLURGICAL  ANALYSIS 

titles,  and  these  are  subject  to  such  great  variation  that  a  mathe- 
matical treatment  of  the  subject  does  not  yield  results  of  a  very 
practical  nature.*  The  most  reliable  way  to  determine  what 
size  of  sample  should  be  taken  from  an  unknown  ore  is  to  sam- 
ple a  large  lot  of  it  in  duplicate.  For  example,  if  the  ore  is  to 
be  shoveled  from  one  place  to  another,  every  fifth  shovelful 
can  be  put  alternately  into  two  receptacles,  so  that  when  the  ore 
is  all  transferred,  each  receptacle  will  contain  duplicate  sam- 
ples, each  a  tenth  of  the  ore.  These  samples  are  then  properly 
prepared  and  assayed.  If  the  assays  from  the  two  samples  are 
not  concordant,  within  the  limits  of  error  in  assaying,  the  whole 
lot  is  sampled  in  duplicate  again,  every  fourth  or  third  shovelful 
being  taken  and  put  alternately  into  two  receptacles  as  before, 
and  the  two  again  assayed.  In  this,  or  in  a  similar  way,  by 
hand  or  by  mechanical  sampler,  the  smallest  lot  that  may  be 
taken  for  a  sample  of  each  of  various  grades  of  ores  has  been 
determined  in  many  mining  districts.  These  results  have  been 
brought  together  and  tabulated  in  convenient  form  by  Prof. 
R.  H.  Richards,  f  In  his  table  which  is  here  reproduced,  it  will 
be  observed  that  in  the  left-hand  column  is  given  the  quantity 
of  ore  that  must  be  taken  in  order  to  obtain  a  fair  sample  of 
the  several  grades  of  ore,  described  at  the  top  of  succeeding 
columns,  when  the  largest  particles  have  the  diameters  given  in 
these  columns. 

For  example,  the  sample  of  rich  ore  (column  5),  whose  coarsest 
particles  measure  5  mm.  in  diameter,  must  contain  500  Ibs., 
but  that  quantity  will  be  sufficient  for  a  sample  of  low-grade 
or  uniform  ore  (column  2)  which  has  its  coarsest  lumps  as  large 
as  18  mm.  Also  the  sample  of  a  rich  ore  whose  largest  particle 

*  E.  D.  Peters,  "  Practice  of  Copper  Smelting,"  8.  "  Ore  Sampling," 
S.  A.  Reed,  School  of  Mines  Quarterly  3,  253,  also  6,  351.  "  The  Theory 
and  Practice  of  Ore-sampling,"  D.  W.  Brunton,  Trans.  Amer.  Inst.  Mining 
Engineers,  25,  826.  "  Principles  of  Ore-sampling,"  A.  Van  Zwaluwenburg, 
Mines  and  Methods,  Oct.,  1909. 

t"  Ore  Dressing,"  2,  852. 


SAMPLING 


11 


Weight  to  be  Taken 
as  Sample. 

Diameter  of  the  Largest  Particle. 

Grams. 

Pounds. 

Very 
Low- 
grade  or 
very 
Uniform 
Ores. 

Low- 
Srade  or 
niform 
Ores. 

Medium 
Ores. 

Medium 
Ores. 

Rich  or 
"Spotted" 
Ores. 

Very  Rich 
or  Exces- 
sively 
"Spotted" 
Ores. 

1 

2 

3 

4 

5 

6 

mm. 

mm. 

mm. 

mm. 

mm. 

mm. 

20,000 

207 

114 

76.2 

50.8 

31.6 

5.4 



10,000 

147 

80.3 

53.9 

35.9 

22.4 

3.8 

5,000 

104 

56.8 

38.1 

25.4 

15.8 

2.7 

2,000 

65.6 

35.9 

24.1 

16.1 

10.0 

1.7 

1,000 

46.4 

25.4 

17.0 

11.4 

7.1 

1.2 

500 

32.8 

18.0 

12.0 

8.0 

5.0 

0.85 



200 

20.7 

11.4 

7.6 

5.1 

3.2 

0.54 

100 

14.7 

8.0 

5.4 

3.6 

2.2 

0.38 

50 

10.4 

5.7 

3.8 

2.5 

1.3 

0.27 



20 

6.6 

3.6 

2.4 

1.6 

1.0 

0.17 

10 

4.6 

2.5 

1.7 

1.1 

0.71 

0.12 

5 

3.3 

1.8 

1.2 

0.80 

0.50 



2 

2.1 

1.1 

0.76 

0.51 

0.32 

1 

1.5 

0.80 

0.54 

0.36 

0.22 

0.5 

1.0 

0.57 

0.38 

0.25 

0.16 

90 

0.2 

0.66 

0.36 

0.24 

0.16 

0.10 

45 

0.1 

0.46 

0.25 

0.17 

0.11 

22.5 

0.05 

0.33 

0.18 

0.12 

9 

0.02 

0.21 

0.11 

4.5 

0.01 

0.15 

2.25 

0.005 

0.10 

, 

measures  1  mm.  in  diameter  must  contain  20  Ibs.,  while  that  of 
a  very  low-grade  ore  of  the  same  size  particle,  would  have  to 
contain  only  0.5  Ib.  This  table  shows  not  only  how  much  should 
be  taken  for  the  original  sample,  but  also  how  much  must  be  taken 
from  the  original  sample  after  it  has  been  crushed  finer  and  mixed, 
so  that  the  portion  taken  will  still  be  a  representative  portion 
of  the  whole. 

After  the  sample  has  been  taken  either  by  hand  or  by  a 
mechanical   sampler   (Fig.   6),   it  is  successively    crushed    and 


12 


METALLURGICAL  ANALYSIS 


FIG.  6. — Vezin  Sampler.  This  sampler  cuts  out  at  regular  intervals  a 
section  across  the  stream  of  crushed  ore  and  is  set  to  take  a  definite 
fraction  of  the  ore  that  passes  through  it. 


'•'^Vi 


fb 


FIG.  7. 


FIG.  8. 


FIG.  9. 


FIG.  7. — The  Sample  is  Shoveled  into  a  Conical  Heap  on  the  Sampling 
Floor.  Each  shovelful  is  dropped  directly  on  the  apex  of  the  cone 
so  that  the  ore  will  roll  down  evenly  on  all  sides  of  the  cone. 

FIG.  8. — The  Cone  is  Flattened  by  Drawing  the  Ore  from  the  Center  Out- 
ward with  the  Shovel  as  the  Sampler  Walks  around  the  Cone.     The 
cone  is  then  quartered  and  opposite  quarters  are  discarded. 
FIG.  9. — Split  Shovel  for  Dividing  the  Sample. 


SAMPLING 


13 


mixed  and  reduced  in  size — in  accordance  with  the  table — by 
coning  and  quartering  (Fig.  7,  8),  by  the  split  shovel  (Fig.  9), 


FIG.  10.— Riffle  for  Dividing  a 
Crushed  Sample  into  Halves. 


FIG.  11. — Riffle  to  be  Placed  on 
Rubber  Cloth  when  Used. 


FIG.  12. — Crusher.     Sectional  View. 


or  by  riffles  (Fig.  10,  11),  until  the  quantity  has  been  reduced 
to  a  few  ounces  (Fig.  12,  13,  13a,  14),  all  of  which  will  pass 
through  a  hundred-mesh  sieve;  and  with  certain  ores — iron 


14 


METALLURGICAL  ANALYSIS 


FIG.  13. — Pulverizer. 


FIG.  13a. — Bucking  Plate  and  Muller 
for  Fine  Grinding  by  Hand. 


FIG.  14.— Ball  Mill  for  Soft  Ore, 
Coal,  etc. 


FIG.  15. — Mechanical  Grinder  with 
Agate  Mortar  and  Pestle. 


THE  OPERATIONS  OF  ANALYSIS  15 

ores  for  instance — much  time  may  be  saved  in  dissolving  the 
ore  if  it  is  ground  still  finer  in  an  agate  mortar.  Good  mechanical 
grinders  (Fig.  15)  may  now  be  obtained  that  require  little  atten- 
tion and  therefore  save  much  time  and  labor. 

THE  OPERATIONS  OF  ANALYSIS 

GRAVIMETRIC 

Weighing.  The  next  step,  after  the  preparation  of  the  sample, 
is  weighing  the  small  portion  that  is  to  be  analyzed.  The 
quality  of  balance  used  and  the  care  taken  in  weighing,  as  in 
sampling,  will  depend  upon  the  values  involved.  With  a  good 
balance,  weighing,  if  due  care  is  exercised,  can  be  made  far  more 
accurate  than  the  other  operations  in  chemical  analysis.  While 
a  high  degree  of  accuracy  in  the  final  result  should  always  be  kept 
in  mind,  it  is  unnecessary  to  make  a  great  outlay  to  secure  the 
highest  degree  of  accuracy  in  one  step  of  an  operation  when  it 
cannot  be  approached  in  the  other  necessary  steps. 

Care  and  Use  of  the  Balance.  The  balance  should  be  set  up 
level  on  a  support  free  from  vibration  in  a  room  of  uniform 
temperature.  It  must  be  kept  free  from  dust,  and  if,  in  making 
a  weighing,  anything  is  spilled  in  the  case,  it  should  be  brushed 
out  after  the  weighing  is  finished.  The  door  of  the  case  should 
always  be  kept  closed,  except  when  the  balance  is  being  used. 
The  same  scale  of  the  balance  should  always  be  used  for  the 
weights,  preferably  the  one  on  the  right-hand  side,  and  the  one  on 
the  left  is  reserved  for  substances  to  be  weighed.  This  will  pre- 
vent the  introduction  of  error,  in  case  the  arms  of  the  balance 
are  not  of  exactly  equal  length.  Only  individual  objects  of 
metal  or  glass  should  be  placed  directly  on  the  metal  pans  of 
the  balance;  finely  divided  materials  such  as  ore,  dry  reagents, 
etc.,  should  be  weighed  on  a  watch  glass,  or  on  a  platinum  pan 
made  for  the  purpose. 

Watch  glasses  of  approximately  equal  weight  can  be  bought 


16  METALLURGICAL  ANALYSIS 

in  pairs  for  use  on  the  balance.  Materials  which  give  up  moisture 
or  gas,  or  absorb  moisture  readily,  should  be  weighed  in  weigh- 
ing bottles.  (Fig.  16.)  The  small  bottle  containing 
a  few  grams  of  the  material  is  closed  with  a  glass 
stopper  and  weighed,  a  portion  of  the  substance  on 
which  the  determination  is  to  be  made  is  then  trans- 
ferred from  the  bottle  to  the  beaker,  or  other  receptacle 
in  which  the  analysis  is  to  begin,  and  the  bottle  with 
its  remaining  contents  again  weighed.  The  difference 
between  the  two  weights  represents  the  quantity  taken 
out. 

Wei  ton"  The   WeiSnts-      The   weights    should    be    tested 

Bottle.        occasionally  to  see  that  they  bear  correct  relations  to 
one  another.      If   appreciable   errors    are  found,  the 
weights  should  be  returned  to  the  instrument  maker  for  correc- 
tion, or   they   may    be    standardized   by  the  chemist  and  the 
necessary  corrections  made  for  each  weighing. 

To  test  the  weights,  place  upon  one  of  the  scales  of  a  delicate 
balance  which  has  arms  of  equal  length  the  1-gm.  weight  taken 
for  the  standard,  and  counterpoise  it  with  small  pieces  of  metal 
placed  on  the  other  scale.  When  the  1-gm.  weight  is  thus  counter- 
poised, transfer  it  to  the  scale  with  the  counterbalancing  metal 
and  test  the  two  2-gm.  weights  in  the  other  pan,  one  after  the 
other.  In  a  similar  manner,  test  the  5-gm.  weight,  and  the  others, 
up  to  the  largest,  by  counterpoising  them  with  the  required  tested 
weights  of  lower  denominations.  Test  the  fractional  weights 
collectively  by  counterpoising  them  with  the  standard  gram; 
the  inequality  should  not  exceed  0.2  mgm.  In  comparing  the 
smaller  weights  with  one  another,  they  should  not  show  a  dif- 
ference as  large  as  0.1  mgm. 

The  Operation  of  Weighing.  First,  see  that  the  balance 
and  watch  glasses  are  clean.  Find  the  zero-point  with  the  balance 
empty,  as  follows:  let  the  beam  down  on  the  knife  edges,  release 
the  pans,  raise  the  door  of  the  case  an  inch  or  so,  and,  with  9 


prow 


THE  OPERATIONS   OF  ANALYSIS  17 

gentle  downward  movement  of  the  hand  in  front  of  the  right 
pan  of  the  balance,  set  the  air  in  motion  sufficiently  to  cause  the 
balance  to  swing.  Close  the  door  of  the  balance  and  take  the 
reading  on  the  graduated  scale  of  two  consecutive  swings  of  the 
pointer  on  one  side,  and  the  intervening  swxing  on  the  other. 
The  zero-point,  or  the  point  at  which  the  balance,  if  left  free  to 
oscillate,  would  come  to  rest,  is  indicated 
by  the  mean  of  those  readings.  For  in- 
stance, if  it  should  swing  to  the  right  of 
the  middle  point  of  the  scale  to  6.8  and 
then  to  the  left  of  the  middle  point  to  4.4 
and  then  again  to  the  right  to  6.4,  we  pro- 
ceed thus:  the  mean  of  the  readings  on  FlG-  17.— Graduated 
,,  .  v  ,  .  ~  „  ,,  ,,  •  ,  /re  Scale  of  Balance  Show- 

tne  right  is  b.b,  then  the  zero-point   (rie;.  ,,  .,         e  ^-    ,. 

?  v     s        mg  Method  of  Finding 

17)  will  be  the  point  on  the  scale  mid-     the  £ero  Point. 

way  between  6.6   on  the    right   and   4.4 

on  the  left  of  the  center  of  the  scale,  or  6.6-4.4  =  2.2;  2.2-^2 
=  1.1;  that  is,  1.1  divisions  to  the  right  of  the  center  of  the 
scale  is  the  zero-point. 

After  the  zero-point  has  been  determined,  arrest  the  pans 
and  lift  the  beam  from  the  knife  edges.  Place  the  object  to  be 
weighed  on  the  left  pan  of  the  balance  and  the  largest  weight 
that  is  judged  to  be  necessary  to  counterbalance  it  on  the  right 
pan.  Then  gently  lower  the  beam  and  release  the  pans.  If 
the  weight  tried  is  found  to  be  too  light,  arrest  the  pans,  lift 
the  beam,  remove  the  weight  and  try  the  next  heavier  weight. 
Continue  in  this  way  until  the  largest  single  weight  is  found  that 
is  lighter  than  the  object  being  weighed;  then  complete  the  weigh- 
ing by  trying  the  lighter  weights,  one  by  one,  in  consecutive 
order  down  to  the  smallest,  and  finally  finish  with  the  rider 
with  the  balance  door  closed.  The  weighing  is  complete  when 
the  rider  is  so  placed  that  the  readings  of  the  needle  to  the  right 
and  to  the  left  indicate  the  same  zero-point  as  when  the  balance 
is  empty.  Five  readings  may  be  taken  instead  of  three,  that  is, 


18  METALLURGICAL  ANALYSIS 

three  on  one  side  and  two  on  the  other.  When  the  rider  is 
finally  adjusted  so  that  the  oscillations  indicate  the  original 
zero-point,  note  the  vacancies  in  the  weight-box  and  the  position 
of  the  rider  and  record  the  weight  in  the  weight-book  opposite 
the  name  of  the  object  weighed,  in  grams  to  the  fourth  decimal 
place.  Then  after  arresting  the  pans  and  lifting  the  beam, 
return  each  weight  to  its  proper  place  in  the  box,  checking  at  the 
same  time  the  recorded  figures  to  make  sure  that  they  are  correct. 

Precautions  in  Weighing.  The  pans  should  always  be 
arrested  before  changing  the  position  of  the  rider  or  before  chang- 
ing any  weight  on  either  pan.  They  should  be  arrested  when 
near  the  middle  of  the  swing,  and  always  before  lifting  the 
beam.  The  beam  should  be  lifted  before  changing  a  weight 
greater  than  0.5  gm.  The  weights  should  be  transferred  with 
the  pincette  and  it  should  be  used  for  nothing  else.  The  door 
of  the  balance  should  always  be  closed  when  taking  final  readings 
to  prevent  the  interference  of  air  drafts. 

Weighing  for  Analysis.  In  weighing  finely  divided  materials 
such  as  ore,  limestone,  steel  drillings,  and  the  like,  it  is  best  to 
take  a  definite  portion,  as  1  gm.,  0.5  gm.,  or  a  factor  weight 
(see  p.  32  for  factor  weights).  In  that  case,  the  weight  repre- 
senting the  quantity  desired  is  placed  in  the  watch  glass  on  the 
right  scale  of  the  balance  and  counterbalanced  by  adding  the 
material  to  be  weighed  by  means  of  a  spatula  to  the  other  scale. 
This  method  is  simple  and  rapid;  it  simplifies  the  keeping  of 

records  and  the  calculation  of  re- 
sults. For  weighing  steel  drillings, 
a  pointed,  magnetized,  steel  wire, 

FIG.  18.— Magnetized  Wire  for    three   or  four   inches   lonS    (FiS-    18)> 
Transferring  Steel  Drillings,      is    useful    in   transferring    small    par- 
ticles  of   steel  to   or  from   the   bal- 
ance to  complete  the  weighing. 

Dissolving.  After  the  sample  has  been  weighed,  it  is 
dissolved  in  order  that  the  element  or  ion  may  be  freed 


THE  OPERATIONS  OF  ANALYSIS  19 

and  subsequently  converted  into  a  form  in  which  its  quantity 
may  be  conveniently  measured.     Most  metallurgical  materials 
are  soluble  in  acids,  and  those  that  are  not  may  be  converted 
into  soluble  form  by  fusing  them  with  suitable  fluxes.     After 
weighing    the    sample    it    should   be   transferred,   with    the   aid 
of  a  small  camel's  hair  brush,  from  the  watch  glass 
directly  to  the  beaker,  casserole,  flask,  crucible,  or 
other  receptacle  in  which  the  analysis  is   to  begin. 
When  the  acid  or  other  solvent  is  added,  if  solution 
does  not  take  place  without  heat,  the  beaker  should 
be  placed  on    the    hot-plate   or   over  a  low  burner 
under  the  hood.      The  quantity  of   the  solvent   to 
be   added  is   usually  given    in    the    method.      The 
solvent  is  measured  approximately  in  a   graduated 
cylinder  (Fig.  19)  and  if  its  volume  is  considerably     FlG     19  _ 
reduced   by  evaporation   before   the  sample  is  dis-      Graduated 
solved,  more  of  the  solvent  should  be  added.      A       Cylinder, 
hot-plate  with  the  heat  applied  under  the  center  is 
convenient;  for,  by  moving  the  determination  towards  the  center 
or  away  from  it,  any  desired  degree  of  heat  may  be  found. 

Reagents.  All  reagents  should  be  tested  as  to  their  purity, 
especially  for  the  quantities  of  those  impurities  which  would 
interfere  with  the  action  of  the  reagent,  or  would  in  any  way 
introduce  error  into  the  result.* 

The  quantity  of  a  reagent  used  in  a  determination  is  measured 
accurately  only  when  the  reagent  serves  as  a  measure,  either 
directly  or  indirectly,  of  the  element  sought.  In  other  cases 
when  only  an  excess  of  the  reagent  is  desired  to  insure  the  com- 
pletion of  a  reaction,  the  quantity  used  may  be  measured  only 
approximately. 

In  the  description  of  the  methods  as  given  in  this  book,  it  is 
assumed  that  the  following  reagents  are  at  hand:   distilled  water; 
hydrochloric   acid,    specific   gravity    1.20;     nitric    acid,    specific 
*  "The  Testing  of  Chemical  Reagents,"  Van  Nostrand  &  Co. 


20  METALLURGICAL  ANALYSIS 

gravity  1.42;  sulphuric  acid,  specific  gravity  1.84;  and  ammonia, 
specific  gravity  0.90.  Where  these  reagents  are  mentioned  with- 
out qualification,  the  above  concentrations  are  meant.  If  other 
concentrations  are  desired,  the  strength  is  indicated  either  by 
specific  gravity,  or  in  the  ratio  by  volume  of  the  concentrated 
reagent  to  water.  By  the  latter  method  the  ratio  is  indicated 
by  a  colon  (:),  which  stands  between  the  two  volumes,  the  volume 
after  the  colon  always  referring  to  water. 

Tables  on  pages  332  to  334  show  how  to  make  the  acids  to  any 
desired  density  by  giving  directly  the  volume  of  the  concentrated 
acid  and  the  volume  of  water  necessary  for  each  concentration. 

Precipitation.  It  should  be  kept  in  mind  that  electrolytes 
are  the  more  completely  ionized  the  more  dilute  the  solution, 
and  that  precipitates  come  down  cleaner  from  a  dilute  solution, 
that  is,  freer  from  substances  adsorbed  from  the  solution.* 
It  should  also  be  remembered  that  no  substance  is  absolutely 
insoluble  in  aqueous  solution;  and  necessarily  the  larger  the 
volume  of  solution,  the  greater  quantity  of  the  precipitate  will 
be  required  for  its  saturation.  If  the  solubility  of  the  precipitate 
is  not  so  small  as  to  be  negible,  precautions  must  be  taken  to 
reduce  the  solubility  to  a  minimum.  This  may  be  done  by 
adding  a  liquid  in  which  the  precipitate  is  less  soluble  than  in 
the  original  solution,  or,  in  the  case  of  an  electrolyte,  by  adding 
an  excess  of  the  precipitant,  or  of  a  soluble  salt  containing  one 
of  the  ions  of  the  precipitate.  For  instance,  if  we  wish  to  pre- 
cipitate SO4  from  solution  as  BaSO4,  we  add  an  excess  of  BaC^. 
The  solution  is  saturated  with  Ba  ions  from  the  BaCb,  which 
reduces  to  a  minimum  the  solution  and  dissociation  of  BaSCU.f 

Precipitates  are  more  easily  filtered  and  washed  if  they  are 
granular  or  crystalline.  They  should,  therefore,  be  left  in  the 
mother  liquor  at  a  moderate  temperature — but  not  boiling — 
as  long  as  circumstances  permit.  By  this  treatment  the  fine 

*Ostwald:     "Foundations  of  Analytical  Chemistry,"  p.   18. 
f  Ibid.,  p.  73. 


THE  OPERATIONS  OF  ANALYSIS 


21 


crystals  are  dissolved  and  redeposited  upon  the  coarse  ones. 
This  enlargement  of  the  crystals,  as  explained  by  Ostwald,  is 
due  to  surface  tension  on  the  boundary  surfaces  between  solids 
and  liquids,  which  tends  to  reduce  the  surface,  thereby  enlarg- 
ing the  individual  grains.* 

Filtration.  The  filters  used  should  have  been  washed  with 
hydrochloric  and  hydrofluroic  acids,  and,  if  for  gravimetric 
work,  the  average  weight  of  ash  should  have  been  determined. 
Very  finely  divided  precipitates  like 
BaSO4will  often  run  through  ordinary 
filter  paper.  If  a  paper  is  selected 
whose  pores  are  smaller  than  the 
particles  of  precipitate,  the  trouble 
of  refiltration  may  be  avoided.  The 
size  of  the  filter  selected  should  be 
determined  by  the  bulk  of  the  pre- 
cipitate, rather  than  by  the  volume 
of  the  solution  to  be  filtered,  and 
the  paper  should  be  folded  to  fit 
the  funnel  snugly.  The  clear  super- 
natant solution  should  be  decanted 
first  and  allowed  to  run  down  a 
glass  rod  into  the  filter  while  the 
precipitate  remains  undisturbed  in 
the  bottom  of  the  beaker.  (Fig.  20.) 
The  clear  solution  runs  through  readily,  after  which  the  precipi- 
tate may  be  washed  by  decantation  or  transferred  to  the  filter 

and  washed  on  the  filter.    The 

1  -  ~II,,,,^JL    filter  paper  should  not  be  filled 

FIG.  21.— "  Policeman."  w*tn  s°luti°n  nearer  to  the  top 

than  5  mm.    If  the  precipitate 

sticks  to  the  beaker,  it  may  be  rubbed  loose  with  a  "  police- 
man "  (Fig.  21;  a  bit  of  small  rubber  tubing  on  the  end  of  a 

*  Ostwald:    "Foundations  of  Analytical  Chemistry,"  p.  22. 


FIG.  20.— Filtering. 


22 


METALLURGICAL  ANALYSIS 


glass  rod)  and  then  washed  into  the  filter  by  inclining  the  beaker 
at  a  high  angle,  with  a  glass  rod  held  with  the  left  hand  across 
the  top  of  the  beaker  and  resting  in  its  lip,  so  that  when  a  jet 
of  water  is  directed  up  into  the  beaker  with  the  right  hand,  it 
will  flow  back  down  the  sides,  carrying  the  precipitate  with  it  to 
the  lip  and  down  the  glass  rod  directly  into  the  filter.  In  this  way 
the  last  traces  of  precipitate  are  transferred  to  the  filter.  (Fig.  22.) 


FIG.  22. — Completing  the  Transfer  of  a  Precipitate  to  the  Filter. 

If  filtering  is  to  be  done  by  gravity,  the  funnels  should  have 
long  stems,  which  are  kept  full  of  solution  while  filtering.  In 
laboratories  where  routine  work  is  done  and  the  same  determina- 
tion must  be  made  on  many  samples,  much  time  is  saved  by  the 
use  of  multiple  stirring  and  filtering  devices  such  as  are  described 
by  Keller  and  shown  in  Figs.  23  and  24.* 

Metallurgical  laboratories  should  be  provided  with  apparatus 
for  filtering  by  suction.  Since  compressed  air  is  also  needed, 
*  Trans.  Amer.  Inst.  Min.  Eng.,  36,  3. 


THE  OPERATIONS  OF  ANALYSIS 


23 


it  is  convenient  to  have  a  pump  which  exhausts  the  air  on  one 
side  of  the  piston  and  compresses  it  on  the  other,  suitable  equaliz- 
ing tanks  being  provided  for  the  compressed  air  and  for  partial 
vacuum.  Before  entering  the  pump  the  air  should  pass  through 
a  scrubber  containing  a  solution  of  sodium  hydroxide  for  the 
removal  of  acid  fumes.  In  small  laboratories,  the  Richards 
pump  may  be  used  for  this  purpose  (Fig.  25),  and,  in  connection 
with  a  Woulf  bottle,  the  air  may  be  compressed  for  a  blast 


FIG.  23. — Stirring  Machine  in  Position  for  Rinsing. 


FIG.  24. — Decanting  and  Filtering  Apparatus.     Position  at  End  of  Filtration. 

lamp.  The  stem  of  the  funnel  is  put  through  a  rubber  stopper 
into  a  filter-flask  which  is  connected  with  the  exhaust.  A  per- 
forated platinum  cone  (Fig.  26)  should  be  put  in  the  funnel 
under  the  filter  to  support  it  when  the  suction  is  turned  on. 
To  save  the  trouble  of  transferring  the  filtrate  from  the  filter- 
flask  to  a  beaker,  by  the  use  of  a  bell-jar,  the  filtrate  may  be 
delivered  to  the  beaker  directly.  The  stem  of  a  funnel  is  intro- 
duced through  a  rubber  stopper  in  the  top  of  the  bell-jar,  under 
which  is  placed  the  beaker  to  receive  the  filtrate.  The  bell-jar 


24 


METALLURGICAL  ANALYSIS 


(Fig.  27)  rests  on  a  smooth  plate  and  the  joint  between  them 
is  sealed  with  vaseline  or  grease.     If  the  bell-jar   has   no   side 


Water  from  Main 


Richards  Pump 


•Waste  Pipe 


FIG.  25. — Richards  Pump  and   Woulf  Bottle  Combined  to  Obtain  Both 

Blast  and  Suction. 


FIG.  26. — Perforated 
Platinum  Cone. 


FIG.  27. — Bell  Jar  Arranged  for  Filtering 
by  Suction  Directly  into  a  Beaker. 


tubulure,   the  air  may  be  exhausted  from  a  tube  introduced 
through  the  stopper. 


THE  OPERATIONS  OF  ANALYSIS 


25 


Use  of  the  Gooch  Crucible.  Precipitates  which  require  only 
drying  or  heating  to  moderate  temperatures  before  weighing  may 
be  filtered  in  a  Gooch  crucible  (Fig.  28),  dried,  and  weighed 
directly.  The  Gooch  crucible  is  attached  to  a  carbon  filter  with 
a  short,  soft  rubber  tube  (Fig.  29),  and  may  be  connected  with 
suction  if  desired.  An  asbestos  felt  is  made  in  the  crucible, 
either  by  shaking  up  asbestos  in  distilled  water  and  pouring  into 
the  crucible  until  the  felt  is  of  the  desired  thickness,  or  the  asbestos 


Rubber 
•'  Tubing 


-Carbon 
filter 


FIG.  28. — Gooch 
Crucible. 


FIG.  29.— Gooch  Crucible  Attached  to 
Filter  Flask  for  Filtering  by  Suction. 


fibers  may  be  put  in  dry  and  pressed  down  with  a  glass  rod. 
The  felt  is  then  washed  with  water  to  carry  away  small  fibers 
that  will  pass  through  the  perforations  of  the  crucible.  The 
crucible  with  felt  is  then  dried  for  an  hour  in  an  air  bath  at  a 
little  above  100°  C.,  cooled  in  a  desiccator  and  weighed.  It 
is  again  attached  to  the  carbon  filter,  and  when  the  filtration  and 
washing  are  completed,  it  is  dried,  cooled,  and  weighed  as  before. 
When  filtering  in  a  Gooch  crucible,  very  strong  suction  should 
not  be  applied,  since  it  causes  the  asbestos  felt  to  pack,  which 
greatly  retards  the  speed  of  filtering. 


26 


METALLURGICAL  ANALYSIS 


Washing  of  Precipitates.  Precipitates  that  settle  readily 
are  best  washed  by  decantation.  Let  the  precipitate  settle, 
carefully  decant  the  clear  solution  through  the  filter,  leaving  the 
precipitate  in  the  beaker,  add  wash  water,  digest  over  the  heat 
as  long  as  desired  and  again  decant.  Repeat  this  treatment  as 
often  as  necessary  and  finally  transfer  the  precipitate  to  the  filter. 

After  the  precipitate  has  been  trans- 
ferred to  the  filter,  it  should  be 
washed  by  directing  the  jet  of  wash 
water  down  against  the  inside  of 
the  funnel,  a  little  above  the  filter 
paper,  carrying  the  jet  around  just 
above  the  edge  of  the  filter  and  then 
down  spirally  into  the  filter.  The 
wash  bottle  may  be  used,  but  it  is 
simpler  and  more  agreeable,  where 
much  work  is  done,  to  wash  from  a 
tank  by  gravity.  This  is  effected 
by  placing  a  tank  for  distilled  water, 
which  is  provided  with  heat  by  gas 
or  electricity,  about  three  feet  above 
the  working  table,  from  which,  with 
a  suitable  rubber  tube,  the  water 
is  conducted  to  the  funnels.  This 

FIG.  30.— An  Elevated  Tin-lined     tube    (Fig.    30)    is  provided   at  the 

lower  end  with  a  wash-bottle  nozzle 
and  a  spring  clamp  for  shutting  off 
the  water.  By  opening  the  clamp 
and  directing  the  nozzle  with  the 
same  hand  the  washing  proceeds  rapidly  from  one  funnel  to 
the  next.  The  rubber  tube  should  be  long  enough  to  permit 
the  operator  to  carry  the  nozzle  from  one  end  of  the  line  of 
funnels  to  the  other. 

The  washing  of  precipitates  would  be  a  comparatively  simple 


Copper  Tank  in  which  Dis- 
tilled Water  is  Heated  for 
Washing  Precipitates  by 
Gravity. 


THE  OPERATIONS  OF  ANALYSIS 


27 


matter  if  the  contaminating  substances  would  freely  leave  the 
surface  of  the  precipitate  and  diffuse  evenly  throughout  the 
wash  water.  In  this  case  four  or  five  washings  would  ordinarily 
be  sufficient,  but,  as  explained  by  Ostwald,  owing  to  adsorption, 
that  is,  the  greater  concentration  of  dissolved  substances  at  the 
surface  of  the  precipitated  particles,  the  number  of  washings 
must  be  greatly  increased,  and  the  washing  should  be  continued 
until  it  is  found  by  testing  the  wash  water  as  it  comes  through, 
that  it  no  longer  contains  the  contaminating  substances.  In 
some  cases  twenty  or  thirty  washes  are  required.  Richards  con- 
siders the  difficulty  of  freeing  precipitates  of  contamination  by 
washing,  due  to  occlusion,  or  the  enclosing  of  solutes  in  the  pre- 
cipitate as  it  is  formed. 

Burning  Precipitates.  When  the  washing  is  complete,  if 
the  precipitate  is  one  that  is  to 
be  burnt  and  weighed,  and  can 
be  burnt  in  contact  with  the 
paper  without  danger  of  re- 
duction, it  can  be  put  in  the 
crucible  and  burnt  without 
previous  drying,  if  the  heat 
is  applied  carefully  at  the  be- 
ginning. If,  on  the  other 
hand,  the  precipitate  is  a 
compound  of  lead,  tin,  or  other 


FIG.  31. — Transferring  a  Dried  Pre- 
cipitate from  the  Filter  Paper  to  a 
Platinum  Crucible. 


metal  easily  reduced  when  in 
contact  with  hot  carbon,  the  precipitate  must  be  dried  and 
transferred  from  the  paper  to  the  crucible  (Fig.  31),  where  it  is 
burnt  out  of  contact  with  the  paper.  The  paper  is  then  held  over 
the  crucible  on  a  platinum  wire  and  burnt  in  a  Bunsen  flame,  the 
ash  being  allowed  to  fall  into  the  crucible. 

When  a  wet  precipitate  is  transferred  from  the  funnel  to  the 
crucible  to  be  burnt  at  once,  the  cover  should  be  put  on  the 
crucible  and  kept  there  until  all  volatile  matter  has  been  driven 


28 


METALLURGICAL  ANALYSIS 


out.  Great  care  should  be  taken  that  the  heat  is  increased  so 
gradually  that  the  precipitate  is  not  thrown  out  by  the  escaping 
steam.  When  all  volatile  matter  has  been  driven  off,  the  cover 
is  removed  from  the  crucible  and  the  temperature  raised  to  oxidize 
the  carbon  of  the  filter,  after  which  the  cover  is  replaced  and  the 
heat  of  the  blast-lamp  applied  if  necessary.  In  burning  a  filter, 
it  should  be  remembered  that  oxygen  is  needed  as  well  as  heat; 
the  flame,  therefore,  should  not  envelop  the  crucible,  but  the 


FIG.  32. — Arrangement  of 
Crucible  and  Cover  for 
Burning  a  Precipitate, 


FIG.  33.— Method  of  Using  Oxygen  in 
Burning  a  Precipitate. 


crucible  should  be  inclined  and  partially  uncovered  (Fig.  32), 
with  the  Bunsen  flame  applied  only  near  the  bottom.  The  cover 
should  be  so  adjusted  that  the  hot  gases  from  the  crucible  can 
escape  upward  while  fresh  air  is  drawn  in  on  each  side  of  the 
cover.  The  carbon  should  be  burned  off  at  as  low  a  tempera- 
ture as  possible  to  avoid  reduction  of  the  precipitate. 

When  rapid  work  is  necessary,  time  may  be  saved  by  burn- 
ing precipitates  in  oxygen.  The  oxygen  may  be  introduced 
into  the  crucible  through  a  clean  clay  tobacco-pipe  (Fig.  33). 
Before  the  pipe  is  lowered  into  the  crucible,  the  flow  of  oxygen 


THE  OPERATIONS  OF  ANALYSIS  29 

must  be  so  regulated  that  it  will  not  blow  the  precipitate 
away. 

The  Care  of  Platinum.  Platinum  is  attacked  by  chlorine, 
and,  therefore,  by  any  combination  of  substances  that  yields 
chlorine,  as  aqua  regia,  etc.;  by  mixtures  of  hydrobromic  and 
nitric  acids;  by  hydriodic  acid  slowly;  and  by  boiling  ferric 
chloride  solution.  Mercury  will  adhere  to  platinum,  forming 
a  plate  on  the  surface,  but  it  may  be  driven  off  by  heat. 

At  high  temperatures,  platinum  is  attacked  by  the  hydrates, 
nitrates,  and  cyanides  of  the  alkalies  and  the  alkaline  earths; 
by  a  mixture  of  sulphur  or  sulphides  with  alkaline  salts ;  by  phos- 
phorus and  arsenic,  and  the  metals  that  form  alloys  with  platinum, 
such  as  lead,  tin,  antimony,  gold,  etc.  Substances  that  contain 
these  elements  in  easily  reducible  form  should  not  be  heated  in 
contact  with  platinum. 

When  charcoal  is  burned  in  contact  with  platinum,  silicon 
is  reduced  from  the  charcoal  and  combines  with  the  platinum, 
making  it  brittle. 

The  reducing  flame  gives  to  platinum  a  dull  gray  appearance, 
and  repeated  heating  and  cooling  promotes  the  growth  of  crystals 
which  increase  in  size  until  they  give  the  surface  of  the  metal 
a  spotted  appearance.  To  prevent  the  growth  of  such  crystals 
and  the  final  cracking  of  the  platinum,  rub  with  sea-sand  held 
on  the  moistened  finger  until  the  surface  of  the  metal  is 
bright. 

To  Clean  Platinum.  If  it  is  known  what  substance  pro- 
duces the  stain  or  discoloration  on  the  platinum,  use  the  best 
solvent  known  for  that  substance,  which  at  the  same  time  will 
not  attack  the  platinum.  For  obstinate  cases,  fuse  a  little  sodium 
carbonate  on  the  stain,  cool,  and  dissolve  by  boiling  with  hydro- 
chloric acid,  and  then  rub  the  platinum  bright  with  sea-sand. 
A  sand-soap  may  be  used,  but  the  sharp  sand  of  the  soap  wears 
the  platinum  away  faster  than  the  round  grains  of  sea-sand. 
Hold  the  sand  on  the  moistened  finger  or  on  a  damp  cloth  when 


30  METALLURGICAL  ANALYSIS 

rubbing  the  platinum.     Do  not  rub  the  platinum  against  a  solid 
lump  of  sand-soap. 

The  Desiccator.    When  the  precipitate  has  been  sufficiently 
heated  in  the  crucible  to  bring  it  to  the  definite  form  in  which 
it   is   to    be   weighed,   the    crucible   is    placed    in   a    desiccator 
(Fig.  34)  while  it  is  still  hot,  but  not  glowing,  to  be  left  to  cool 
before  it  is  weighed.     The  desiccator  may  con- 
tain any  good  absorbent  of  moisture.     Either 
concentrated  sulphuric  acid  or  calcium  chloride 
serves  the   purpose  well,   and   the    desiccator 
should  be  occasionally  replenished  with  a  fresh 
supply  of  the  desiccating  agent  to  maintain  its 
efficiency.     If  sulphuric  acid  is  the  dryer  used 
FIG  34  — Desic-     m  tne  desiccator,  glass  beads  should  be  put  in 
cator.  with  the  acid  to  prevent  its  flowing  too  easily 

and  being  thrown  against  the  crucible  when  the 
desiccator  is  handled.  The  contact  between  the  desiccator  and  its 
cover  should  be  made  air-tight  by  applying  occasionally  a  mixture 
of  vaseline  and  paraffine. 

Objects  weighed  when  warm,  weigh  less  than  when  cold, 
owing  to  upward  currents  produced  in  the  air  about  them,  which 
buoy  them  up;  and  the  rate  at  which  moisture  is  deposited 
upon  them  from  the  air  depends  upon  the  temperature;  there- 
fore, they  should  always  be  cooled  in  a  desiccator  and  weighed  at 
room  temperature,  or  all  weighings  made  at  as  nearly  the  same 
temperature  as  possible. 

Weighing  Precipitates.  After  the  crucible  has  cooled  in  the 
desiccator,  usually  from  fifteen  to  twenty  minutes,  it  is  care- 
fully taken  from  the  desiccator  with  a  pair  of  clean  forceps 
or  tongs  and  placed  upon  the  balance  for  weighing.  Care  should 
be  taken  not  to  touch  the  crucible  with  the  hands  until  the  final 
weighing  has  been  made.  Weigh  as  quickly  as  possible  and  record 
the  weight  in  the  weight-book.  Return  the  crucible  with  its 
contents  to  the  desiccator  with  the  forceps,  carry  it  back  to  the 


THE  OPERATIONS  OF  ANALYSIS  31 

working  table  and  heat  it  again  for  ten  minutes,  cool  and  weigh 
again  as  before,  and  if  the  weight  does  not  agree  with  the  former 
weight,  repeat  this  treatment  until  the  weight  is  constant.  If 
a  very  large  crucible  or  other  large  object  is  weighed  it  should 
be  counterbalanced  by  a  similar  object  on  the  other  balance  pan 
to  neutralize  the  effect  of  deposition  of  moisture  from  the  atmos- 
phere. 

Calculating  Results.  The  results  of  analyses  are  usually 
expressed  in  parts  per  hundred,  or  per  cent.  If  the  precipitate 
finally  weighed  is  in  the'  form  in  which  it  is  to  be  reported,  it  is 
only  necessary  to  divide  its  weight  by  the  weight  of  the  sample 
taken  for  analysis  and  multiply  the  result  by  100.  For  example, 
if  the  CaO  from  0.5  gm.  of  limestone  weighs  0.1931  gm.,  to  find 
the  percentage  of  lime  in  the  limestone,  the  question  may  be 
simply  stated  thus: 

If  in  0.5  gm.  of  limestone  there  are  0.1931  gm.  of  lime,  in 
100  parts  of  limestone  there  are  how  many  parts  of  lime? 

0.  5:0.  1931  =  100  :x 


It  is  evident  in  cases  pf  this  kind  that  the  calculation  is 
simplified  by  taking  a  definite  weight  of  the  sample  that  is 
simply  expressed,  as  1  gm.,  0.5  gm.,  or  0.2  gm.,  because  that 
number  must  be  used  as  divisor. 

When  the  precipitate  weighed  is  not  in  the  form  in  which 
it  is  to  be  reported,  the  quantity  in  the  desired  form  must  be 
calculated  from  the  weight  of  the  precipitate.  For  example, 
if  the  precipitate  of  BaSO4  from  5  grams  of  steel  weighs  0.0232 
gm.,  what  is  the  percentage  of  S  in  the  steel?  We  first  find 
the  weight  of  S  in  0.0232  gm.  BaSO4,  and  with  that  weight 
proceed  as  in  the  last  example.  To  find  the  weight  of  S  in  0.0232 
gm.  of  BaS04,  we  multiply  by  the  factor  for  S  in  BaSO4.  The 


32  METALLURGICAL  ANALYSIS 

factor  is  the  number  which  expresses  the  weight  of  S  in  one  part 
of  BaS04,  and  is  obtained  as  follows: 

The  molecular  weight  of  BaSCU  is  233.44,  being  composed 
of 

1  atom  of  Ba,  atomic  weight 137.37 

1  atom  of  S,  atomic  weight 32 . 07 

4  atoms  of  O,  atomic  weight 16=   64. 


233.44 

Then,  if  in  233.44  parts  of  BaSO4,  there  are  32.07  parts  of 

32  07 

S,  there  is  in  one  part  of  BaSO4  —  —  =0.13738  part  of  S. 

2oo.4 1 

The  factor,  then,  for  S  in  BaS04  being  determined  once  for 
all  as  0.13738,  we  proceed  as  follows:  if  one  part  (or  gram) 
of  BaS04  has  0.13738  part  (or  gram)  of  S,  0.0232  gm.  of  BaSO4 
will  contain  0.0232X0.13738  =  0.003187  gm.  of  S.  Then,  pro- 
ceeding as  in  the  first  example  above,  we  find  the  percentage 
of  S  as  follows : 

0.003187X100  7j 


The  whole  operation  may  be  expressed  in  one  equation: 
0.0232X0.13738X100  _n  nr/17 

"  p — U.Uu~r/. 

O 

Factor  Weights.  In  the  above  example,  if  we  had  weighed 
not  5  gms.  of  steel,  but  0.13738  gm.,  or  better,  0.1374  gm.,  this 
latter  number  would  become  the  denominator  in  the  above 
equation  and  the  solution  would  be  simplified,  for  the  denominator 
would  then  be  the  same  as  the  factor  for  S  in  the  numerator 
and  the  two  would  cancel.  We  would  then  only  have  to  multiply 


• 


VOLUMETRIC  ANALYSIS  33 

the  weight  of  BaS04  by  100,  or  move  the  decimal  point  two 
places  to  the  right.  A  weight  of  this  kind  is  called  a  factor 
weight  and  is  used  to  simplify  the  calculation  of  the  result. 
In  the  case  above,  the  weight  0.1374  gm.  is  too  small  a  quantity 
of  steel  for  the  sample,  for  the  yield  of  BaSC>4  from  that  quan- 
tity of  this  steel  (0.000637  gm.)  is  so  small  that  errors  in  manipu- 
lation would  be  greatly  magnified;  a  simple  multiple  as  20  or 
50  times  this  factor  weight,  can  be  used  and  still  the  calculation 
remain  extremely  simple.  Such  factor  weights  are  much  used 
in  routine  gravimetric  work  in  which  the  form  weighed  must  be 
converted  by  calculation  into  another  form  before  the  percentage 
is  estimated. 


VOLUMETRIC  ANALYSIS 


Volumetric  Apparatus.  Volumetric  analysis  demands  the 
use  of  graduated  flasks,  pipettes,  and  burettes.  The  chemist 
should  test  such  apparatus  to  see  if  it  is  correctly  graduated, 
and,  if  it  is  not,  he  should  determine  the  errors  and  make  the 
necessary  corrections.  This  is  done  by  weighing  the  distilled 
water  contained  by  the  apparatus,  at  the  temperature  at  which 
it  was  graduated — usually  marked  on  the  apparatus — or  by 
comparing  the  volume  contained  with  that  which  is  held  by 
similar  specially  standardized  apparatus  sold  by  dealers. 

Measuring  flasks  (Fig.  35)  are  usually  graduated  to  hold  the 
quantity  indicated  at  the  temperature  marked  on  the  flask, 
but  some  flasks  have  a  second  graduation  higher  up  on  the  stem 
to  which  they  should  be  filled  to  deliver  the  indicated  quantity. 
Pipettes  (Fig.  36)  and  burettes  (Figs.  37,  38)  deliver  the  quan- 
tities indicated,  and  should  be  given  half  a  minute  to  drain. 

*  Titration  methods  and  colorimetric  methods  are,  strictly  speaking, 
not  volumetric  methods  in  the  sense  that  gas  analysis  is;  for  in  the  former 
we  must  still  use  the  balance  for  weighing  the  sample  and  for  standardizing 
the  solutions,  but  the  determination  of  the  weight  of  the  substance  sought 
is  accomplished  through  volumetric  operations, 


34  METALLURGICAL  ANALYSIS 

The  point  of  the  pipette  should  touch  the  side  of  the  receiv- 
ing vessel  to  deliver  the  last  drop;  do  not  blow  out  the  last 
drop. 

To  fill  a  pipette,  place  the  upper  end  in  the  mouth  and 
draw  the  solution  in  until  the  meniscus  stands  somewhat  above 
the  graduation  of  the  pipette.  Withdraw  the  pipette  from  the 


/I 


FIG.  35. 


FIG.  36. 


FIG.  37. 


FIG.  38. 

FIG.  35. — Graduated  Flask.  FIG.  36. — Pipette.  FIG.  37. — Burette. 

FIG.  38. — Burette  that  Fills  to  Zero  Automatically  with  Overflow  Cup 

and  Side  Tube  for  Filling  from  Reservoir. 

mouth  and  quickly  place  the  index  finger  of  the  right  hand  over 
the  upper  end  to  hold  the  solution  in  the  pipette.  Then  turn  the 
pipette  with  the  left  hand,  admitting  the  air  slowly  until  the 
meniscus  falls  to  the  graduation.  Press  firmly  again  with  the 
index  finger  to  prevent  further  admission  of  air  until  the  pipette 
is  brought  in  position  to  be  discharged.  Poisonous  liquids  and 
those  giving  off  unpleasant  gases  should  be  drawn  into  the  pipette 
by  attaching  the  upper  end  of  the  pipette  with  a  rubber  tube  to 


VOLUMETRIC  ANALYSIS  35 

the  exhaust  tap  on  the  work  table.  The  suction  can  be  con- 
trolled by  operating  the  tap  or  by  pressure  on  the  rubber 
tube. 

For  the  accurate  reading  of  the  burette,  some  chemists  prefer 
a  burette  float,  but  for  regular  routine  work  it  is  sufficiently 
accurate  to  read  the  bottom  of  the  meniscus,  especially  if  a  strip 
of  white  paper  be  held  just  back  of  the  burette.  To  read  the 
burette  when  it  contains  very  dark-colored  solutions,  such  as 
potassium  permanganate  solution,  it  is  necessary  to  hold  a 
light  just  behind  the  burette  to  render  the  meniscus  visible. 
A  light  may  be  supplied  by  a  simple  jet  attached  with  a  rubber 
tube  to  the  gas  tap  on  the  table. 

Cleaning  Solution.  All  apparatus  must  be  kept  scrupulously 
clean.  This  applies  especially  to  volumetric  apparatus,  which 
must  be  free  from  grease  and  all  other  foreign  matter  so  that 
solutions  will  flow  out  evenly  and  not  leave  drops  adhering  to 
the  sides.  An  excellent  cleaning  solution  is  made  by  adding 
10  gms.  of  potassium  dichromate  to  a  liter  of  commercial 
sulphuric  acid.  After  using  the  cleaning  solution  it  should  not 
be  thrown  away,  but  returned  to  the  bottle  for  future  use.  The 
apparatus  to  be  cleaned  should  be  left  full  of  the  cleaning  solu- 
tion for  several  hours,  and  thoroughly  washed  with  distilled 
water  after  the  cleaning  solution  has  been  returned  to  its  bottle. 

Titration.  Instead  of  precipitating,  filtering  out,  and  weigh- 
ing a  substance,  it  is  better  in  many  cases  to  measure  it  while 
in  solution  by  the  method  of  titration.  For  carrying  out  the 
process  of  titration  it  is  necessary  to  prepare  a  solution  of  a 
reagent  which  will  react  in  a  definite  way  with  the  substance 
to  be  determined.  This  solution  must  have  a  certain  deter- 
mined strength  and  is  called  a  standard  solution.  It  is  also 
necessary  to  provide  means  for  determining  when  the  reac- 
tion is  complete.  A  reagent  used  for  this  purpose  is  called  an 
indicator.  To  make  an  analysis  by  titration,  then,  we  put  the 
sample  in  solution  in  such  form  that  the  ion  sought  will  react 


36  METALLURGICAL  ANALYSIS 

in  a  definite  way  with  the  standard  solution.  The  standard 
solution  is  run  in  from  a  burette  until  the  indicator  shows  that 
the  reaction  is  complete;  by  noting  the  volume  of  the  standard 
solution  that  has  been  used,  and  knowing  its  value  per  cubic 
centimeter  in  the  substance  being  determined,  it  is  easy  to 
calculate  the  amount  of  that  substance  present. 

Standard  Solutions.  Standard  solutions  are  made  to  con- 
tain a  definite  amount  of  the  active  agent  in  every  cubic  centi- 
meter. Two  kinds  of  standard  solutions  are  in  general  use  — 
normal  solutions,  and  empirical  standard  solutions. 

Normal  Solutions.  A  normal  solution  is  a  standard  solution 
which  has  in  a  liter  that  quantity  of  reagent  which  contains 
1.008  gms.  (the  atomic  weight)  of  replaceable  hydrogen,  or  the 
equivalent  of  that  amount  of  hydrogen  in  some  other  active  agent, 
as  35.46  gms.  chlorine  or  8.0  gms.  of  oxygen.  A  normal  solution 
of  hydrochloric  acid  will,  therefore,  contain  36.468  gms,  of  HC1  per 
liter,  and  such  a  solution  of  sulphuric  acid,  49.043  gms.  H2SO4  per 
liter.  A  normal  solution  of  potassium  permanganate  should  con- 
tain 31.606  gms.  of  the  salt  per  liter,  since  the  weight  of  K2Mn2Os 
which  contains,  in  available  oxygen,  the  equivalent  of  1.008 

Q  -j  r*    f\£* 

gms.  hydrogen  is         '  ,  =31.606  gms.     (In  K2Mn2O8  there  are 


5    atoms  of   available  oxygen.     K2Mn2Og  =  K2O-f  2MnO+50.) 
In  like  manner  a  normal  solution  of  K2Cr2O7  will  contain  49.03 


gms.  of   the   salt  (K2Cr2O7  =  K20+Cr203-r-3O.  =  49.03); 

JXo 

and  such  a  solution  of  iodine  will  contain  126.92  gms.  of  iodine 
(I2+H20  =  2HI+O). 

If  the  normal  solution  is  not  a  convenient  strength,  any 
suitable  multiple  as  the  half,  fifth,  tenth,  hundredth,  or  the 
twice  normal  way  be  used.  A  normal  standard  solution  is 
convenient  if  the  one  solution  is  to  be  used  for  different  purposes 
and  on  different  substances,  but  if  the  standard  solution  is  to  be 
used  for  one  particular  process,  as  is  usually  the  case  in  metal- 


VOLUMETRIC  ANALYSIS  37 

lurgical  analysis,  the  empirical  standard  solution  is  the  more 
useful  and  convenient. 

Empirical  Standard  Solutions.  An  empirical  standard  solu- 
tion is  made  so  that  1  cc.  of  it  will  be  equivalent  to  a  simple 
definite  value  of  the  substance  to  be  determined,  as  0.01  gm. 
or  0.005  gm. ;  1  per  cent  or  0.5  per  cent  when  a  sample  of  definite 
weight  is  worked  upon.  Empirical  standard  solutions  are  made 
by  calculating,  from  the  reaction  involved,  the  amount  of  the 
titrating  reagent  required  to  react  with  0.01  gm.,  0.005  gm., 
or  any  other  desired  amount  of  the  substance  to  be  determined, 
and  then  weighing  out  as  many  times  this  amount  as  there  are 
cubic  centimeters  in  the  whole  volume  of  solution  to  be  made. 

Preparation  of  an  Empirical  Standard  Solution.  A  standard 
solution  of  potassium  permanganate  of  such  value,  for  example, 
that  1  cc.  will  oxidize  0.01  gm.  of  iron  from  the  ferrous  to  the 
ferric  form  is  made  as  follows.  The  reaction  which  takes  place 
between  KMn(>4  and  ferrous  iron  in  the  presence  of  £[2864  is  as 
follows: 

10FeS04+2KMnO4+8H2S04  = 

5Fe2(S04)3+K2S04+2MnS04+8H20. 

If  10  atoms  of  Fe"  are  oxidized  by  the  available  oxygen  from  2 
molecules  of  KMnCU,  0.01  gm.  of  Fe"  will  require  for  its  oxidi- 
zation 0.0056601  gm.  of  KMnO4,  as  shown  by  the  following 
proportion: 

10(55.84)  :  2(158.03)  =0.01  :  0.0056601, 

55.84  being  the  atomic  weight  of  iron  and  158.03  the  molecular 
weight  of  KMnO4. 

Having  determined  the  amount  of  KMnCU  required  in  1  cc., 
if  we  wish  to  make  a  liter  of  such  a  solution,  we  weigh  out  1000 
times  0.0056601  gm.,  or  5.6601  gm.,  dissolve  it  in  distilled  water, 
and  dilute  the  solution  to  1  liter  in  a  graduated  flask. 


38  METALLURGICAL  ANALYSIS 

Standardizing  Solutions.  In  order  that  a  standard  solu- 
tion have  the  strength  intended,  it  must  be  made  with  great  care. 
The  purity  of  the  reagent  must  be  known,  and  any  impurity 
allowed  for,  the  weighing  must  be  accurate,  there  must  be  no 
loss  after  weighing,  the  reagent  must  not  be  subjected  to  con- 
ditions that  will  change  its  form  before  or  after  it  is  put  in  solu- 
tion, and  the  temperature  of  the  solution  should  be  the  same 
when  it  is  used  for  titration  as  when  it  was  made.  As  a  safe- 
guard against  errors  from  these  sources,  a  solution  that  is  to  be 
used  for  titration  should  be  standardized  against  a  reagent 
of  known  purity  to  determine  its  actual  strength  per  cubic  centi- 
meter, that  is,  an  exact  quantity  of  such  reagent  is  weighed 
out,  put  in  solution  and  titrated  under  as  nearly  as  possible 
the  same  conditions  as  exist  when  determinations  are  made 
on  unknown  materials.  There  should  be  the  same  impurities 
present  and  in  the  same  amounts,  and  the  volume  to  be  titrated 
should  be  the  same  when  standardizing  as  when  making  regular 
determinations.  See  that  the  burette  is  perfectly  clean,  and 
if  it  is  wet  with  distilled  water,  rinse  it  out  with  some  of  the 
solution  that  is  to  be  standardized  before  filling  for  the  test. 
Place  the  burette  in  a  vertical  position  in  a  burette  clamp  attached 
to  a  stand.  Nearly  fill  the  burette  with  the  solution  to  be 
standardized.  Open  the  tap  and  let  a  little  of  the  solution 
run  out,  in  order  to  fill  the  point  of  the  burette  below  the  tap, 
and  to  bring  the  meniscus  down  to  the  graduations.  See  that 
a  bubble  of  air  is  not  held  just  below  the  tap.  Now  read  the 
burette  at  the  bottom  of  the  meniscus  and  record  the  reading. 
Let  the  solution  run  from  the  burette  into  the  solution  to  be 
titrated,  stirring  or  shaking,  until  the  reaction  is  complete 
as  shown  by  the  indicator.  Care  must  be  taken  to  stop  the 
titration  at  the  exact  end-point,  therefore,  as  the  end-point 
is  approached,  the  solution  must  be  run  in  very  slowly — drop 
by  drop.  When  the  end-point  is  reached,  close  the  tap  of  the 
burette,  and  after  waiting  half  a  minute  for  the  solution  to 


VOLUMETRIC  ANALYSIS  39 

run  down  the  sides,  read  the  burette  and  record  the  reading. 
The  difference  between  the  two  readings  of  the  burette  indi- 
cates the  volume  used  in  the  titration.  After  some  practice 
the  burette  can  be  read  to  the  second  decimal  place.  The  record 
should  stand  thus: 

Second  reading  of  the  burette 37 . 58  cc. 

First  reading  of  the  burette 1 . 24 

Volume  used  in  titration 36 . 34 

To  find  the  value  of  1  cc.  of  the  solution  in  the  burette,  divide 
the  weight  of  the  substance  acted  upon,  after  correcting  for 
impurities,  by  the  volume  used  in  the  titration. 

Correcting  a  Standard  Solution.  If  a  solution  is  tested  with 
a  .view  to  correcting  what  remains,  to  the  exact  strength  desired, 
a  definite  portion,  as  100  cc.,  should  be  taken  out  for  the  test, 
so  that  the  remaining  volume,  which  is  to  be  corrected,  may 
be  known. 

To  indicate  the  method  of  correcting  a  standard  solution, 
we  will  suppose  that  the  potassium  permanganate  solution  in 
the  example  above,  when  tested  against  a  known  weight  of  iron, 
is  found  not  to  have  the  value,  0.01  gm.  of  Fe  per  cubic  centimeter, 
but  1  cc.  proves  to  be  equivalent  to  only  0.0096  gm.  of  Fe.  If 
we  have  900  cc.  of  the  solution  left,  we  may  correct  it  as  follows. 
If  1  cc.  of  the  solution  is  equivalent  to  only  0.0096  gm.  of  iron, 
it  does  not  contain  0.0056601  gm.  of  KMnO4,  but  only  0.0054337 
gm. 

0.01  :  0.0056601  =  0.0096  :  0.0054337 

There  must  be  added,  then,  to  each  of  the  900  cc.  remaining 
(0.0056601 -.0054337)  0.0002264  gm.  of  the  salt,  or  to  the 
total  volume  (0.0002264x900)  0.0238  gm.  The  calculation  is 
simplified  by  reducing  to  this  form: 

/1-.0096\ 


40  METALLURGICAL  ANALYSIS 

On  the  other  hand,  if  the  solution  is  too  strong,  it  may  be 
corrected  as  follows:  let  us  suppose  that  1  cc.  is  equivalent  to 
0.0107  gm.  of  Fe  instead  of  0.01  gm.,  then  each  cubic  centimeter 
of  the  solution  has  in  it,  not  0.0056601  gm.  of  the  salt,  but 
0.006056307  gm. 

0.01  :  0.0107  =  0.0056601  :  0.0060563. 

There  is,  therefore,  in  each  cubic  centimeter  of  the  solution  too 
much  KMnO4  by  0.0003962  gm.,  and  in  the  900  cc.  remaining  there 
are  0.35658  gm.  (0.0003962X900)  too  much  of  the  salt.  This  is  a 
sufficient  quantity  of  the  salt  to  make  63  cc.  of  the  correct 
strength  (0.35658 -=-0.0056601  =  63).  We  have  then  only  to 
add  63  cc.  of  distilled  water  to  the  solution  to  dilute  it  to  the 
correct  value.  This  problem  stated  in  one  equation  may  be 
reduced  to  the  form: 

(1.07-1)900  =  63. 

Factor  Weights  for  Standard  Solutions.  It  is  not  always 
easy  to  make  a  standard  solution  of  an  exact  predetermined 
value,  nor  is  it  easy  to  keep  it  at  an  exact  value.  The  object 
of  making  the  standard  solution  so  that  1  cc.  will  be  equivalent 
to  a  simple  definite  value,  as  0.01  gm.  of  the  substance  to  be 
determined,  is,  of  course,  to  simplify  the  arithemtical  calcula- 
tion of  the  result  after  titration.  If  we  have  a  standard  perman- 
ganate solution  of  the  value  of  0.01  gm.  of  Fe  per  cubic  centi- 
meter, and  use  1  gm.  of  iron-ore  for  analysis,  the  number  of  cubic 
centimeters  of  solution  used  in  the  titration  will  represent  directly 
the  percentage  of  iron  in  the  ore.  Suppose,  for  example,  it  is 
observed  after  titration  in  such  a  case  that  62  cc.  of  the  standard 
solution  had  been  used  in  titration,  then  the  calculation  would 
be  as  follows: 


VOLUMETRIC  ANALYSIS  41 

It  is  evident  from  this  equation  that  the  calculation  would 
remain  equally  simple  if  the  weight  of  the  ore  taken  is  always 
just  100  times  the  value  of  the  solution.  If  the  KMnCU  solu- 
tion should  have  the  value  0.0096  instead  of  0.01,  we  would  only 
have  to  weigh  out  0.96  gm.  of  ore  instead  of  1  gm.  to  preserve 
the  simplicity  of  calculation.  It  is  simpler  then,  instead  of  try- 
ing to  make  and  keep  a  solution  at  an  exact  definite  value,  to 
standardize  it  as  often  as  necessary,  and,  as  its  value  changes, 
change  the  weight  of  ore  taken  to  correspond  with  it. 

Indicators.  In  all  titrations  there  must  be  a  means  pro- 
vided for  detecting  when  the  reaction  is  complete,  that  is,  when 
the  substance  being  measured  has  all  been  acted  upon.  This 

l-p&int  is  detected  in  a  variety  of  ways,  for  example,  by  the 
Formation  of  a  precipitate,  as  in  titrating  cyanide  with  silver 
nitrate;  by  the  failure  of  a  precipitate  to  form,  as  in  the  Gay- 
Lussac  method  for  silver;  by  the  standard  solution  giving  its 
color  to  the  solution  titrated,  when  the  action  is  complete,  as 
in  the  permanganate  titration;  by  the  change  or  disappearance 
of  the  color  of  the  solution  titrated,  as  in  the  cyanide  method 
for  copper;  by  a  change  of  color  in  drops  of  a  test  solution, 
to  which  drops  of  the  solution  being  titrated  are  added  from 
time  to  time,  as  the  titratien  proceeds,  or  by  the  change  of 
color  due  to  the  presence  of  a  test  solution,  or  indicator,  added 
to  the  solution  titrated.  The  last  method  is  the  one  employed 
when  the  end-point  is  marked  by  a  change  in  the  solution  titrated 
from  the  alkaline  to  the  acid  condition,  or  vice  versa.  Several 
indicators  are  in  use  for  detecting  this  change.  They  vary 
in  their  sensitivity  and  in  their  suitability  for  different  uses. 
For  convenience  the  more  common  ones  are  given  below  with 
their  adaptability  to  different  uses. 

Phenolphthalein,  colorless  with  acids  and  pink  with  alkalis, 
is  good  for  hydrochloric,  nitric,  sulphuric,  and  the  organic 
acids;  and  also  for  the  alkalis  NaOH,  KOH,  Ba(OH)2  and 
Ca(OH)2.  It  is  not  good  for  ammonia,  nor  in  the  presence 


42  METALLURGICAL  ANALYSIS 

of  C02,  but  may  be  applied  after  expelling  the  CC>2  by 
boiling. 

Methyl  Orange,  pink  with  acid  and  yellow  with  alkalis,  is 
good  for  hydrochloric,  nitric,  and  sulphuric  acids;  the  hydrates, 
carbonates,  and  bicarbonates  of  the  alkalis,  and  also  for  am- 
monia. 

Cochineal,  purple  red  with  acids,  and  blue  with  alkalis,  is 
good  with  ordinary  mineral  acids  and  alkalis,  including  ammonia. 
It  is  also  reliable  in  the  presence  of  CO2,  but  not  with  the  organic 
acids. 

The  reagent  used  for  detecting  the  end-point  will  be  described 
under  each  titration  method. 

COLORIMETRY 

Many  substances  regularly  determined  in  metallurgical  anal- 
ysis, when  in  solution  and  in  certain  definite  forms  give  to  the 
solutions  characteristic  colors,  which  may  be  used  as  a  basis  for 
the  quantitative  determination  of  these  substances. 

The  intensity  of  the  color  of  a  solution  depends  upon  three 
elements,  or  factors.  They  are :  the  quantity  of  coloring  matter 
used,  the  volume  of  the  solvent  in  which  it  is  held,  and  the  thick- 
ness of  the  solution  through  which  the  light  passes  before  enter- 
ing the  eye.  It  is  well  known  that  if  we  keep  two  of  these  quan- 
tities constant  and  vary  the  third  in  a  determinate  way  until 
two  solutions  are  alike  in  color,  we  can  estimate  the  quantity 
of  coloring  matter  in  one,  if  the  quantity  in  the  other  is  known. 
These  three  variables  form  the  basis  of  three  classes  of  methods 
in  colorimetry,  and  of  three  types  of  colorimeters.  When  two 
solutions  are  brought  to  agreement  in  color  by  the  addition  of 
coloring  matter  to  one,  the  amount  added  is  the  measure  of  that 
in  the  other.  If  the  agreement  is  effected  by  dilution,  the  color- 
ing matter  is  then  proportional  to  the  volumes.  If  they  are 
brought  to  equality  by  changing  the  thickness  of  the  sections 


COLORIMETRY 


43 


observed,   the   quantity   of   coloring   matter  is   then  inversely 
proportional  to  the  measurements  of  these  sections.* 

In  laboratories  where  the  first  method  is  used,  a  series  of 
solutions  is  prepared  (Fig.  39)  with  varying  amounts  of  the 
standard,  representing  the  percentages  from  the  lowest  to  the 
highest  demanded  in  that  laboratory.  For  instance,  the  first 
may  contain  0.01  gm.  of  the  color-producing  substance,  the 


FIG.  39. — Series  of  Standard        FIG.  40. —        FIG.  41. — Camera  for  Eggertz 
Solutions  for  Colorimetry.       Eggertz  Tubes.  Tubes. 

second,  0.03  gm.,  the  third,  0.05  gm.,  etc.  Then,  if  the  sample 
is  dissolved  and  diluted  to  the  same  volume  as  the  standards, 
in  a  similar  tube,  its  place  in  the  series  is  easily  found  and  its 
value  determined  at  once.  Theoretically,  this  is  the  best  colori- 
metric  method  known,  but  it  is  not  so  practical  as  some  others, 
on  account  of  the  large  number  of  standards  required,  and  the 
necessity  for  frequent  renewals  due  to  their  lack  of  permanency. 

*C.  H.  White,  Jour.  Am.  Chem.  Soc.,  34,  639. 


44 


METALLURGICAL  ANALYSIS 


The  second  method,  proposed  by  Eggertz,*  is  usually  carried 
out  in  two  graduated  tubes  of  equal  bore  (Figs.  40,  41).  The 
two  solutions,  the  standard  and  the  unknown,  are  diluted  until 
the  colors  are  the  same  when  the  tubes  are  held  between  the 
observer  and  a  uniform  light.  The  ratio  existing  between  the 
quantities  of  coloring  matter  in  the  two  tubes  is  then  equal  to 


FIG.  42.  FIG.  43. 

FIG.  42. — Colorimeter  in  which  Hollow  Glass  Wedges  are  used  to  Vary 

the  Depth  of  Solution  Examined. 

FIG.   43. — Colorimeter  in  which   Solid   Glass   Plungers   Lowered  into   the 
Solutions  Change  the  Thickness  of  the  Sections  Compared. 

the  ratio  between  the  volumes  of  the  two  solutions.     Since  three 
of  these  quantities  are  known  the  fourth  is  readily  estimated. 

In  the  third  method,  equal  quantities  of  the  standard  and 
the  unknown  are  dissolved  in  equal  volumes  of  the  solvent, 
and  the  thickness,  or  depth,  of  the  solutions  under  examination 
*  Chemical  News,  44,  173,  Fern  Kontorets  Analer,  1862,  p.  54. 


IRON  ORES— SAMPLING  45 

is  varied  until  the  colors  are  the  same.  The  percentages  of 
coloring  matter  are  then  inversely  proportional  to  the  thickness 
of  the  sections.  Several  colorimeters  (Figs.  42,  43)  have  been 
devised  for  varying  and  measuring  the  thickness  of  solutions 
under  examination.  These  instruments  are  usually  constructed 
and  graduated  in  such  a  manner  that  the  desired  percentage 
may  be  read  off  at  once.  With  these  instruments,  comparisons 
can  be  quickly  made,  and  any  number  of  readings  may  be  taken 
and  averaged  without  changing  the  volumes  of  the  solutions. 
The  solutions  are  not  diluted  by  guess  as  in  the  Eggertz 
method,  and  preconceived  notions  of  the  value  of  the  material 
cannot  influence  the  operator,  since  he  cannot  see  the  graduations 
until  the  colors  are  matched. 

METHODS  OF  ANALYSIS  IN  THE  METALLURGY 
OF  IRON  AND  STEEL 

ANALYSIS   OF   ORES 

Sampling  Iron  Ore.     For  the  general  principles-  of  sampling 
see  page  8,  and  for  the  quantity  to  be  taken,   and  the   size  to 


FIG.  44. — Sampling  Trowel        FIG.  45. — Sampling  Pick  for  Drawing 
for  Friable  Ore.  Ore  from  well  below  the  Surface. 

which  the  lumps  should  be  crushed  before  quartering  down 
the  sample,  see  the  table  on  page  11.  For  the  applica- 
tion of  the  table,  ordinary  iron  ores  would  be  classed  as  very 
uniform,  low-grade  material. 

Sampling  Ore  in  Cars.     Soft  ores  may  be  sampled  with  a 
garden' trowel  (Fig,  44)  or  the  sampling  pick  (Fig.  45).    Before 


46 


METALLURGICAL  ANALYSIS 


taking  the  sample,  remove  three  inches  of  the  surface  at  the 
point  where  the  sample  is  to  be  taken  and  then  dig  into  the 
ore  with  the  trowel  or  sampling  pick,  take  up  the  sample,  and 
deposit  it  in  an  iron  pail.  Since  it  is  not  practicable  to  mix 
ore  in  cars  previous  to  sampling,  it  should  be  kept  in  mind  that 
the  accuracy  of  the  sample  increases  as  the  number  of  points 
from  which  it  is  taken  is  increased.  The  U.  S. 
Steel  Corporation  takes  at  least  15  samples  from 
50-ton  and  12  from  25-ton  cars  (Fig.  46),*  of  2  to 
3  ozs.  each;  that  is,  the  total  sample  contains  not 
less  than  1J  Ibs.  from  each  small  car  and  2  Ibs. 
from  each  large  car.  Samples  from  ten  cars  may 


6     o 


o 

0 

o 

0 

:O 

0 

0 

0 

0 

0 

0 

0 

0 

0 

c 

FIG.  46. — Parallel  System  of  Sampling  Ores. 


be  combined  into  one.  The  fact  that  this  very  small  sample 
is  representative  indicates  that  the  ore  is  extremely  uniform 
in  character.  The  points  from  which  the  samples  are  taken  should 
be  as  evenly  spaced  as  possible  over  the  surface  of  the  ore.  If  a 
lump  is  found  at  a  point  from  which  a  sample  is  to  be  taken, 
a  small  piece  is  broken  from  the  lump  for  the  sample;  the  size 
of  this  piece  will  depend  upon  the  size  of  the  lump;  if  the  lump 
is  average  ore  in  the  space  represented  by  that  sample,  the 
chip  taken  off  for  the  sample  will  be  as  large  as  the  usual 
sample. 

The  rope-net  system  in  use  at  some  of  the  hard-ore  mines  in 
the  Lake  Superior  district  is  best  for  the  even  spacing  of  points 

*  J.  M.  Camp,  J.  Ind.  Eng.  Chem.,  1,  107-15.     Also  Electrochem.  Met. 
Ind.,  7,  65-72. 


IRON   ORES— SAMPLING 


47 


from  which  samples  are  to  be  taken.  A  rope  net  of  18-in.  mesh 
(Fig.  47)  is  placed  over  the  car,  the  knots  or  the  squares  indi- 
cating the  points  at  which  samples  are  to  be  taken. 

Moisture  Sample.  If  the  regular  sample  is  taken  from  well 
below  the  surface,  a  portion  of  it — 2000  grams  or  so — may  be 
put  in  a  tin  box  or  jar  with  tightly  fitting  cover  for  a  moisture 
sample.  If  a  special  sample  is  taken  for  moisture,  it  is  taken 
from  well  below  the  surface,  and  three  samples,  equally  spaced, 
are  taken  from  each  car. 

Sampling  a  Cargo.  A  cargo  may  be  sampled  by  taking  a  few 
ounces  from  each  grab  as  it  is  unloaded,  by  means  of  a  scoop 


LJL— , I  _J 

FIG.  47. — Rope  Net  System  of  Sampling  for  Hard  Ores. 

attached  to  a  suitable  handle.  This  method,  however,  is  more 
expensive  than  taking  samples  from  the  surface  while  unloading 
is  going  on.  The  latter  method  is  adopted  by  the  U.  S.  Steel 
Corporation.  Before  unloading  begins,  samples  are  taken  from 
the  cone  of  ore  under  each  hatch;  then  after  unloading  has  pro- 
ceeded far  enough  at  a  hatch  to  expose  the  bottom  of  the  vessel, 
the  sloping  faces  of  ore  exposed  are  then  carefully  sampled. 
The  total  sample  of  the  cargo  should  be  made  up  of  at  least  nine- 
tenths  from  the  faces,  and  not  more  than  one-tenth  from  the 
surface  of  the  cones.  A  cone  is  sampled  by  taking  samples  a 
foot  apart  along  two  lines  which  cross  at  the  apex  of  the  cone 
and  end  directly  under  the  edge  of  the  hatch  midway  between 
the  center  and  the  side  of  the  boat  as  shown  in  Fig;  48. 


48 


METALLURGICAL  ANALYSIS 


A  face  is  sampled  by  climbing  up  the  face,  using  a  ladder,  if 
necessary,  and  taking  samples  from  points  a  foot  apart  (Fig.  49) 
along  lines  equally  spaced  4  ft.  apart. 

Preparation  of  the  Sample.  The  sample  is  dried,  if  necessary, 
at  100°  and  crushed  to  pass  a  half-inch  mesh  screen,  or  finer  (see 
table  on  p.  11).  Thoroughly  mix  the  ore  and  quarter  it  alter- 
nately until  only  one-quarter  of  the  original  sample  remains. 
Crush  this  to  one-quarter  inch,  mix  and  sample  it  down  as  before 
until  about  2  Ibs  remain.  Grind  this  to  pass  a  20-mesh  screen 
or  finer,  roll  well  and  take  out  about  3  ozs.,  dry  at  100°,  grind  on 


FIG.  48. — Cargo  Sampling — 
The  Cone. 


FIG.  49. — Cargo  Sampling — 
The  Face. 


a  bucking  board  to  100  mesh,  or  finer  in  an  agate  mortar  (see 
p.  14)  and  place  in  a  stoppered  bottle  and  reserve  for  analysis. 


MOISTURE 

The  moisture  sample  should  contain  not  less  than  2000  gms.> 
and  should  be  carefully  protected  from  loss  of  moisture  until 
weighed  (see  Moisture  Sample,  p.  47).  It  is  evenly  spread  out 
not  more  than  1  in.  deep  in  a  pan,  and  dried  at  100°  to  a  constant 
weight  (4  to  6  hours,  or  over  night) .  The  loss  in  weight  is  moist- 
ure. Sometimes  a  weight  of  2  Ibs.  is  used  for  the  moisture 
sample,  in  which  case  the  loss  in  weight  multiplied  by  1000  gives 
the  moisture  in  1  ton. 


IRON  ORES— COMBINED  WATER 


HYGROSCOPIC  WATER 

To  reduce  the  results  of  an  analysis  to  the  basis  of  dry  ore, 
it  is  necessary  to  determine  the  moisture  or  hygroscopic  water  in 
the  powdered  sample  when  it  is  analyzed. 

Heat  a  clean  platinum  crucible  to  drive  off  the  moisture, 
cool  it  in  a  desiccator,  weigh  it,  and  then  weigh  and  transfer 
to  it  about  1  gm.  of  the  ore.  Heat  it  about  an  hour  on  a  toluene 
bath  or  in  an  air  bath  held  at  105°  C.  to  110°  C.  (See  p.  70.) 
Cool  in  a  desiccator  and  weigh.  The  loss  in  weight  is  hygroscopic 
water. 

COMBINED  WATER  * 

Blow  a  small  bulb  at  one  end  of  a  hard  glass  tube  (Fig.  50) 
which  is  about  20  cm.  long  and  6  mm.  internal 
diameter  and  another  near  the  middle.  Warm 
the  tube  to  dry  it  thoroughly;  the  drying  is 
hastened  by  drawing  the  air  from  it  at  the  same 
time  by  introducing  into  the  bulb-tube  a  smaller 
glass  tube  attached  to  the  suction  tap  by  a 
rubber  tube.  Cool  and  weigh  the  tube.  Intro- 
duce into  the  bulb  at  the  end,  about  half  a  gram 
of  ore  through  a  thistle  tube,  not  letting  the  ore 
touch  the  sides  of  the  weighed  tube.  Weigh  the 
tube  containing  the  ore.  The  weight  of  the 
empty  tube  deducted  leaves  the  weight  of  the 
ore  introduced.  Hold  the  tube  in  a  horizontal 
position  and  gradually  heat  the  bulb  containing 
the  ore  in  the  Bunsen  flame,  keeping  the  tube 
cool  from  the  middle  to  the  open  end  by  wrap- 
ping it  with  cloth  or  filter  paper  wet  with  cold 
water.  Do  not  use  so  much  water  that  drops 
run  down  to  the  hot  part  of  the  tube.  Turn 
the  tube  in  the  flame  so  that  the  bulb  does  not 

*  Method  of  S.  L.  Penfield,  Am.  Jour.  Sci.,  Third  Series,  48,  31,  1894- 


FIG.  50.  — Bulb 
Tube  for  De- 
termining Com- 
bined Water. 


50  METALLURGICAL  ANALYSIS 

become  soft  enough  to  flow.  The  heating  should  be  continued  at 
least  fifteen  minutes,  and  the  blast  lamp  should  be  used  if  minerals 
are  known  to  be  present  that  give  up  water  with  difficulty.  When 
the  water  has  all  been  driven  out  of  the  sample  and  has  been 
condensed  in  the  middle  of  the  tube  and  while  the  bulb  is  still 
hot,  grasp  it  with  forceps  or  tongs  and  pull  it  away,  sealing 
up  the  end  of  the  tube  with  the  flame.  Dry  the  outside 
of  the  tube,  cool,  and  weigh  it.  Then  warm  the  tube  to  drive 
out  the  water,  sucking  out  the  moisture  as  before  the  first 
weighing,  and  then  cool  and  weigh  it  again.  The  difference 
between  the  last  two  weights  represents  the  total  water.  From 
the  total  water  deduct  moisture  which  has  been  previously 
determined,  to  find  the  weight  of  combined  water.  Reduce 
the  weight  to  per  cent  in  the  usual  way.  (See  p.  31.) 

LOSS  ON  IGNITION 

The  sample  is  weighed  in  the  same  manner  as  for  hygroscopic 
water  and  heated  at  the  highest  temperature  of  the  blast  lamp 
for  thirty  minutes.  The  hygroscopic  water,  the  combined  water, 
carbon  dioxide,  and  other  volatile  substances,  if  present,  will 
be  driven  out;  carbonaceous  matter  burned;  and  ferrous  com- 
pounds oxidized  to  ferric  compounds. 

It  serves  as  a  rough  guide  to  the  water  and  C02  in  limestone, 
and  to  the  water,  in  materials  free  from  other  volatile  substances 
and  from  elements  subject  to  oxidation. 

IRON  IN  ORES 

POTASSIUM  PERMANGANATE — MARGUERITTE  METHOD 

Outline.  The  iron  is  dissolved  from  the  ore  in  hydrochloric 
acid.  It  is  then  reduced  to  the  ferrous  condition  with  zinc, 
sulphuric  acid  added,  and  the  quantity  of  the  iron  is  measured 
by  titrating  it  with  a  standard  solution  of  potassium  permanganate. 


IRON  IN  ORES— PERMANGANATE  METHOD  51 

Reagents.     Potassium  chlorate,  KClOa, 

Pure  Zinc,  Zn.* 

Standard  Potassium  Permanganate  Solution.  Make  the  per- 
manganate solution  in  the  manner  described  on  page  37,  using 
2.83  gm.  of  KMnCU  per  liter.  This  solution  should  be  equiv- 
alent to  0.005  gm.  of  Fe  per  cubic  centimeter,  and  if  it  is 
carefully  prepared  with  chemically  pure  KMnCU  and  distilled 
water  that  has  been  previously  boiled  with  a  little  KMnCU, 
the  error  should  not  be  greater  than  one-half  of  1  per  cent. 
Freshly  prepared  solutions  of  permanganate  usually  contain 
small  amounts  of  Mn(>2,  either  originally  in  the  salt  as  an  impur- 
ity, or  reduced  from  it  by  dust  or  other  impurities  in  the  water 
or  in  the  bottle  in  which  it  is  kept,  and  this  induces  the  formation 
of  more  MnC>2  with  a  corresponding  weakening  of  the  solution. 
After  dissolving  the  KMnO4,  the  MnC>2  should  be  filtered  on 
asbestos  or  the  solution  decanted  from  it,  before  diluting  to  the 
final  volume. 

Filter  paper  should  not  be  substituted  for  asbestos,  as  it 
would  reduce  the  KMnCU.  The  container  for  the  permanganate 
solution  should  have  been  previously  cleansed  with  the  cleaning 
solution  (p.  35)  and  then  with  pure  water.  If,  before  standardiz- 
ing, the  solution  is  allowed  to  age  for  several  days,  the  clear 
solution  decanted  into  a  clean  bottle,  and  kept  away  from  dust 
and  sunlight,  it  should  keep  indefinitely  with  very  little  change 
in  strength. 

Standardization  of  Permanganate  Solution.  Weigh  about 
1  gm.  of  ferrous  ammonium  sulphate  FeSO^NH^SCU-GH^O. 
Dissolve  it  in  20  cc.  of  water  to  which  has  been  added  5  cc.  of 
hydrochloric  acid.  Add  about  3  gm.  of  granulated  zinc  and 
then  add  10  cc.  of  sulphuric  acid  mixed  with  20  cc.  of  water. 

*  Zinc  should  not  be  used  as  a  reducing  agent  for  iron  in  ores  carrying 
titanium,  since  part  of  the  titanium  is  also  reduced  and  is  subsequently 
oxidized  with  the  Fe  by  titration,  vitiating  the  result.  For  titaniferous 
ores  use  either  the  method  on  p.  59  or  that  on  p.  62. 


52  METALLURGICAL  ANALYSIS 

When  the  zinc  is  all  dissolved,  dilute  with  distilled  water  to  500 
cc.  and  titrate  at  once  before  the  iron  becomes  partially  oxidized 
by  exposure  to  the  air. 

So  large  a  quantity  as  3  gms.  of  zinc  is  not  necessary  for  the 
reduction  of  the  iron  for  it  is  already  in  the  ferrous  condition 
except  a  small  amount  which  may  have  become  oxidized  by 
exposure  of  the  solution  to  the  air,  but  the  zinc  is  added  to 
produce,  as  nearly  as  possible,  the  conditions  which  exist  when 
the  ore-solution  is  titrated. 

Multiply  the  weight  of  ferrous  ammonium  sulphate  taken, 
by  its  factor  for  iron  (14.24  if  it  is  known  that  the  salt  conforms 
exactly  to  the  formula),  and  divide  this  weight  of  iron  by  the 
number  of  cubic  centimeters  required  for  the  titration.  This 
gives  the  value  of  1  cc.  of  the  permanganate  solution  in  iron. 
Make  three  or  four  such  tests  that  do  not  vary  more  than  0.0001 
gm.  from  each  other  and  average  the  results. 

In  order  that  the  same  conditions  may  exist  when  standardizing 
a  solution  as  when  regular  titrations  are  made  of  unknown  ores,  iron 
ores  in  which  the  iron  has  been  accurately  determined  are  often  used 
for  standardizing,  but  it  is  evident  that  we  must  have  an  accurately 
standardized  solution  before  we  can  prepare  such  a  standard  ore.  It 
is  therefore  necessary  to  have  recourse  finally  to  a  standard  whose 
composition  has  been  determined  gravimetrically.  Ferrous  ammonium 
sulphate  made  and  kept  with  ordinary  care  does  not  usually  vary  much 
from  the  theoretical  composition,  yet  a  quantity  that  is  to  be  used 
for  standardizing  should  be  carefully  analyzed  for  iron  gravimetrically. 
The  method  for  this  determination  follows. 

IRON  IN  FERROUS  AMMONIUM  SULPHATE — GRAVIMETRIC  METHOD 

Weigh  accurately  about  0.5  gm.  of  ferrous  ammonium  sulphate, 
FeS04(NH4)2SO4-6H2O.  Transfer  it  to  a  No.  4  beaker  and 
dissolve  in  50  cc.  of  water  to  which  has  been  added  10  drops  of 
hydrochloric  acid. 

If  water  alone  were  used  for  the  solvent,  basic  salt  would  be  pre- 
cipitated by  hydrolysis.  HC1  readily  dissociates,  saturating  the  solu- 


IRON  IN  ORES— PERMANGANATE  METHOD  53 

tion  with  H  ions,  which  prevents  dissociation  of  the  water  into  H  and 
OPI.  There  are  therefore  no  OH  ions  available  for  the  formation  of 
basic  salt. 

Heat  to  boiling.  Add  nitric  acid  drop  by  drop  until  the 
solution  turns  yellow  or  red,  through  brown. 

Not  more  than  8  or  10  drops  are  required  if  the  solution  is  kept 
at  the  boiling-point. 

3FeCl2+HN03+3HC.l=3FeCl3+NO+2H20. 

Oxidation  is  necessary,  since  NH4OH  does  not  completely  precipitate 
iron  in  the  ferrous  form. 

Dilute  with  hot  water  to  500  cc.  Add  while  stirring  5  cc. 
ammonia. 

FeCl3+3NH4OH  =Fe(OH)3+3NH4Cl. 

Basic  ferric  sulphate  is  precipitated  in  neutral  solution,  therefore, 
the  ammonia  should  be  stirred  in  quickly  to  render  all  portions  of  the 
solution  alkaline  as  soon  as  possible. 

Heat  to  boiling.  Remove  from  the  heat  and  let  the  ferric 
hydroxide  settle.  Decant  the  clear  solution  through  a  9  cm. 
filter,  leaving  the  precipitate  in  the  beaker.  Wash  twice  by 
decantation  with  100  cc.  hot  water  (see  p.  21)  transfer  the  pre- 
cipitate to  the  filter  and  wash  on  the  filter  with  hot  water,  never 
letting  the  precipitate  get  cold  until  the  washing  is  complete. 
The  washing  is  complete  when  the  wash  water  comes  through 
free  from  chlorides.  Collect  2  or  3  cc.  of  the  wash  water  on  a 
watch  glass  as  it  runs  from  the  funnel,  add  a  drop  of  nitric  acid 
and  then  test  for  chlorides  with  a  solution  of  silver  nitrate. 

Nitric  acid  is  added  to  neutralize  ammonia,  which  if  present  would 
dissolve  the  silver  chloride. 

If  the  chlorides  are  not  washed  out,  the  high  temperature  at  which 
the  precipitate  is  burnt  will  form  ferric  chloride  which  is  easily  volatilized 
and  lost. 


54  METALLURGICAL  ANALYSIS 

The  precipitate  of  ferric  hydroxide  should  be  filtered  as  soon  as  it 
settles;  long  contact  of  the  ammoniacal  solution  with  the  glass  may 
contaminate  the  precipitate  with  silica  dissolved  from  the  glass. 

Place  the  moist  filter  with  its  contents  in  a  platinum  or 
porcelain  crucible  (see  note  below)  that  has  been  cooled  in  a 
desiccator  and  weighed,  cover  the  crucible,  and  carefully  drive 
off  the  moisture  and  volatile  part  of  the  filter  paper  at  so  low 
a  temperature  that  the  escaping  gases  are  not  ignited.  When 
the  volatile  matter  is  all  out,  uncover  the  crucible  and  carefully 
burn  the  carbon  at  as  low  a  temperature  as  possible  with  free 
access  of  air  to  prevent  the  reduction  of  ferric  to  magnetic  oxide. 
When  the  carbon  is  all  burnt,  heat  the  precipitate  to  a  high 
temperature  for  a  few  minutes  with  a  small  blast  flame  directed 
against  the  bottom  of  the  crucible,  and  away  from  the  top. 

2Fe(OH)3=Fe203+3H20. 

A  high  temperature  is  required  to  drive  off  the  last  traces  of  water- 
on  the  other  hand  it  induces  the  formation  of  Fe304,  especially  if  reduc- 
ing gases  are  allowed  to  enter  the  crucible.  In  "  Methods  for  the 
Analysis  of  Iron  and  Steel  Used  in  the  Laboratories  of  the  American 
Rolling  Mill  Co.,"  page  26,  it  is  pointed  out  that  the  ignition  of  ferric 
oxide  in  platinum  induces  the  formation  of  Fe304,  and  it  is  suggested  that 
the  precipitate  be  ignited  and  weighed  in  a  porcelain  crucible  placed 
inside  a  platinum  crucible. 

Cool  in  a  desiccator  and  weigh.  Heat  again  at  a  high  tem- 
perature for  a  few  minutes,  cool  and  weigh.  Repeat  this  treat- 
ment until  the  weight  is  constant.  Calculate  the  weight  of  Fe 
in  the  Fe2O3  (Factor  0.6994)  and  the  percentage  in  the  salt. 

Additional  Methods  of  Standardization.  Iron  wire  in  which 
the  iron  has  been  carefully  determined  may  be  used  for  standard- 
izing permanganate  solutions.  The  wire  is  carefully  cleaned, 
wound  into  a  coil  (on  a  pencil  or  glass  rod),  weighed,  and  treated 
by  the  method  below  for  the  determination  of  iron  in  ore. 

Blair*  recommends  the  use  of  a  solution  of  ferric  chloride 
*  "  The  Chemical  Analysis  of  Iron,"  seventh  edition,  p.  236. 


IRON  IN  ORES— PERMANGANATE  METHOD  55 

made  from  wrought  iron  free  from  manganese  and  arsenic, 
and  in  which  the  iron  and  phosphorus  have  been  accurately 
determined. 

The  oxidizing  power  of  permanganate  solution  may  be 
measured  by  oxalic  acid,  but  the  solution  must  be  hot  when 
titrated,  and  the  other  conditions  under  which  the  titration  is 
made  are  not  the  same  as  when  solutions  of  ore  are  titrated. 

5H2C204  •  2H2O + 2KMnO4 + 3H2SO4  = 

K2S04+2MiiS04+10CO2+10H20. 

This  latter  objection  applies  also  to  Lunge's  method  of  standardiz- 
ing the  solution.  By  this  method  a  measured  volume  of  the 
solution  is  decomposed  with  hydrogen  peroxide  and  sulphuric 
acid,  the  available  oxygen  liberated,  collected  and  measured  in  a 
gas  burette.* 

Fe  in  Ore.  Weigh  0.5  gm.  of  ore  or  a  factor  weight  (see 
p.  40).  Transfer  it  to  a  300  cc.  beaker  or  casserole. 

Add  10  cc.  of  hydrochloric  acid,  cover  with  a  watch  glass,  and 
raise  the  temperature  but  do  not  boil. 

Fe203+6HCl=2FeCl3-{-3H20.  According  to  this  reaction,  0.108 
gm.  HC1  will  dissolve  .5  gm.  Fe203.  In  10  cc.  of  hydrochloric  acid 
1.20  sp.gr.  at  15°  there  are  4.68  gm.  of  HC1;  however,  HC1  is  driven 
off  by  heat,  and  if  the  ore  does  not  dissolve  readily  it  may  be  necessary 
to  add  more  acid. 

If  a  solution  of  ferric  chloride  boils,  iron  is  carried  away  by  the 
vapor  mechanically. 

Add  a  few  crystals  of  KClOs  to  destroy  carbonaceous  matter. 

In  the  titration  some  permanganate  would  be  reduced  by  the  car- 
bonaceous matter  if  it  were  not  destroyed,  and  it  would  also  give  the 
solution  a  color  that  would  persist  after  the  iron  had  been  reduced, 
making  it  impossible  to  detect  by  the  loss  of  color  when  reduction  is 
complete. 

*Chem.  Ind.,  1885,  168;  Olsen,  "Quantitative  Analysis,"  p.  298. 


56  METALLURGICAL  ANALYSIS 

When  the  solution  of  the  iron  is  complete  and  the  residue 
is  white,  or  if  the  acid  appears  to  have  no  further  action,  evaporate 
off  most  of  the  free  acid  (to  about  5  cc.)  at  a  low  heat;  do  not 
boil. 

There  should  be  only  a  little  HC1  left,  for  in  titration  a  somewhat 
concentrated  solution  of  hydrochloric  acid,  or  a  weak  solution  if  hot, 
reacts  with  KMn04  as  follows: 

2KMn04+16HCl=2KCl+2MnCl2+8H20+5Cl2. 

This  reaction  may  be  prevented,  however,  by  the  addition  of  a  few 
grams  of  manganous  sulphate  before  titration. 

If  it  is  suspected  that  iron  remains  undissolved  in  the  residue,  as 
will  be  the  case  if  the  ore  has  not  been  finely  ground  or  if  it  contains 
a  silicate  or  titanate  of  iron,  dilute  with  15  cc.  of  hot  water,  filter,  wash 
once  or  twice  with  hot  water,  place  the  filter  with  the  residue  in  a 
platinum  crucible,  burn  the  paper,  cool,  add  1  cc.  each  of  sulphuric 
acid  and  hydrofluoric  acid,  evaporate  until  sulphuric  acid  fumes  begin 
to  come  off,  and  transfer  the  solution  from  the  crucible  to  the  filtrate 
containing  the  greater  part  of  the  iron. 

Instead  of  treating  the  residue  with  sulphuric  and  hydrofluoric  acids, 
the  iron  may  be  extracted  from  it  as  follows:  after  burning  the  filter 
paper  and  cooling,  add  2  or  3  gms.  of  sodium  carbonate  and  fuse,  digest 
the  fusion  with  hot  water,  which  leaves  the  ferric  oxide  as  a  precipi- 
tate, filter  out  the  ferric  oxide,  dissolve  it  in  a  little  hydrochloric  acid 
and  add  it  to  the  main  solution  of  iron. 

When  the  iron  is  all  in  solution  and  only  a  little  free  hydro- 
chloric acid  remains,  add  about  3  gm.  of  granulated  zinc  to 
reduce  the  ferric  to  ferrous  chloride. 

Zn+2HCl=ZnCl2+H2, 
2FeCl3+H2  =2FeCl2+2HCl. 

When  the  brown  color  of  ferric  chloride  has  disappeared  and 
the  solution  is  clear,  or  if  the  action  on  the  zinc  ceases,  add  10 
cc.  of  sulphuric  acid  which  has  been  mixed  with  20  cc.  of  water. 

When  the  iron  is  all  reduced  (the  solution  becoming  color- 
less) and  the  zinc  is  all  dissolved,  transfer  the  solution  to  a  large 


IRON  IN  ORES— PERMANGANATE  METHOD 


57 


beaker  or  white  dish,  being  careful  to  wash  out  all  of  the  iron 
solution  from  the  original  beaker,  dilute  with  cold  distilled  water 
to  about  500  cc.  and  titrate  with  standard  permanganate  solu- 
tion, stirring,  until  a  faint  permanent  pink  pervades  the  whole 
solution. 


For  the  method  of  titrating,  reading  the  burette,  and  calculating 
the  result,  see  pages  35  and  39. 

REDUCTION  OF  THE  IRON  BY  MEANS  OF  THE  JONES  REDUCTOR 

If  many  reductions  are  to  be  made  with  zinc,  the  process  is 
much  more  quickly  carried  out  by 
the  use  of  the  reductor.  This  re- 
ductor  *  in  its  simplest  form  (Fig.  51) 
consists  of  a  glass  tube  about  60  cm. 
in  length,  the  upper  half  of  which  has 
an  internal  diameter  of  25  mm.  with 
a  funnel  top,  and  the  lower  half  is 
drawn  down  to  a  diameter  of  6  mm. 
The  tube  is  provided  with  a  glass  tap 
at  the  point  where  the  diameter  is 
reduced.  Glass  wool  is  placed  in  the 
tube  above  the  tap  to  a  depth  of  10 
to  15  mm.  to  support  the  column 
of  zinc.  The  large  part  of  the  tube 
is  then  filled  to  the  funnel  with 
amalgamated  zinc.  The  zinc  is  amal- 
gamated to  prevent  its  rapid  con- 
sumption. To  prepare  amalgamated 
zinc,  put  into  a  beaker  enough 
granulated  zinc  (through  20-  on  30- 


Suction 


FIG.  51. — Reductor. 


*  Blair,  "Chemical  Analysis  of  Iron,"  seventh  edition,  p.  94. 


58  METALLURGICAL  ANALYSIS 

mesh  screen)  to  fill  the  tube,  cover  it  with  distilled  water,  add 
about  5  gm.  of  mercury  and  5  cc.  sulphuric  acid,  and  stir  vigor- 
ously with  a  glass  rod.  In  a  few  minutes  the  zinc  is  amalga- 
mated and  ready  to  be  transferred  to  the  reductor. 

Use  of  the  Reductor.  Attach  a  filter  flask  to  the  reductor 
with  a  perforated  rubber  stopper  and  connect  the  filter  flask  to 
the  suction.  Prepare  a  dilute  solution  of  sulphuric  acid  (25 
cc.  of  sulphuric  acid  in  a  liter  of  water)  and  pass  200  cc. 
of  it  through  the  reductor,  keeping  the  zinc  always  covered 
with  solution. 

If  air  comes  in  contact  with  the  zinc,  hydrogen  peroxide  is  formed, 
which,  after  being  absorbed  by  the  iron  solution,  reacts  later  with  the 
permanganate  when  the  iron  solution  is  titrated,  vitiating  the  result. 

Discard  this  wash  solution,  reconnect  the  flask  and  run  a 
blank,  in  the  manner  following,  to  see  how  much  permanganate 
solution  is  required,  owing  to  traces  of  iron  in  the  zinc,  to  produce 
the  pink  end-point.  Pass  300  cc.  of  the  dilute  sulphuric  acid 
solution  through,  never  letting  the  surface  of  the  solution  in  the 
funnel  of  the  reductor  fall  down  to  the  zinc,  disconnect  the 
filter  flask  and  titrate  directly  into  the  flask.  The  quantity 
required  to  produce  the  end-point  must  be  deducted  from  all 
titrations  made  on  solutions  passed  through  the  reductor. 

When  the  insoluble  residue  has  been  filtered  from  the  solu- 
tion of  ore  and  most  of  the  hydrochloric  acid  has  been  driven 
out  by  evaporation,  dilute  the  solution  to  about  100  cc.  with  the 
dilute  sulphuric  acid  solution  (25  cc.  acid  to  a  liter)  and  pass 
it  through  the  reductor  into  a  clean  filter  flask.  Wash  all  the 
iron  solution  from  the  beaker,  with  the  very  dilute  sulphuric 
acid  and  pour  it  through  the  reductor.  Follow  this  with  more 
of  the  dilute  sulphuric  acid  solution  until  200  cc.  of  this  solu- 
tion have  passed  through,  then  follow  this  with  100  cc.  of  dis- 
tilled water,  never  letting  the  air  come  in  contact  with  the 
zinc,  and  finally  leaving  the  funnel  partially  filled  with  water. 


IRON  IN  ORES— PERMANGANATE  METHOD  59 

Disconnect  the  filter  flask  and  titrate  directly  into  it  with  the 
standard  permanganate  solution,  deduct  the  quantity  required 
for  the  blank  and  calculate  the  result. 

Additional  Reducing  Agents.  As  noted  on  page  51,  zinc 
should  not  be  used  for  reducing  iron  in  titaniferous  ores.  For 
such  ores,  stannous  chloride,  sulphurous  acid,  ammonium  bisul- 
phite, hydrogen  sulphide,  or  some  other  reducing  agent  should 
be  used.  The  method  of  reduction  by  stannous  chloride  is  very 
rapid  and  satisfactory,  and  is  applicable  with  either  the  potassium 
dichromate  method  or  the  potassium  permanganate  method, 
if,  before  titrating  with  the  latter,  manganous  sulphate  and 
phosphoric  acid  are  added. 

POTASSIUM  PERMANGANATE  METHOD  FOR  IRON 
REDUCTION  WITH  STANNOUS  CHLORIDE — ZIMMERMAN-REINHARDT  METHOD 

Reagents.  Stannous  Chloride  Solution.  Dissolve  250  gms. 
SnCb  in  100  cc.  hydrochloric  acid  (1.2),  dilute  with  water  to 
1  liter. 

Mercuric  chloride  solution.  A  saturated  solution  of  pure 
HgCb  in  water. 

'•  Titrating  Mixture  "  Manganous  sulphate  and  phosphoric 
acid  solution.  Dissolve  90  gms.  MnSCU  in  650  cc.  of  water, 
add  175  cc.  sulphuric  acid  (1.84),  and  then  175  cc.  phosphoric 
acid  (1.75  sp.  gr.). 

Standard  permanganate  solution.     (See  p.  51.) 

Fe  in  Ore.  Weigh  .5  gm.  of  ore  and  transfer  it  to  a  small 
porcelain  crucible. 

Heat  over  a  Bunsen  burner  for  a  few  minutes  at  low  redness 
to  destroy  carbonaceous  matter. 

A  high  heat  makes  the  ore  more  difficult  to  dissolve. 

Place  the  crucible  with  the  ore  in  a  400  cc.  beaker. 
Add  10  cc.  of  hydrochloric  acid  and  4  cc.  of  stannous  chloride 
solution. 


60  METALLUKGICAL  ANALYSIS 

Stannous  chloride  hastens  solution  by  reducing  the  iron,  but  care 
must  be  taken  that  too  much  stannous  chloride  is  not  added.  Stop 
the  addition  when  the  solution  clears.* 

Heat  to  dissolve  the  iron.  When  the  solution  begins  to  turn 
yellow  add  stannous  chloride  solution  drop  by  drop  to  reduce 
the  iron.  Finally,  when  all  the  iron  is  dissolved  from  the  ore 
and  the  volume  of  solution  has  been  reduced  by  evaporation  to 
about  10  cc.,  add  stannous  chloride  solution  drop  by  drop  until 
the  color  just  disappears,  then  add  one  drop  more. 

2FeCl3+SnCl2  =2FeCl2+SnCl4. 

Reduction  by  stannous  chloride  is  effected  best  in  a  concentrated 
hot  solution.  If  the  solution  is  cool  or  dilute  the  reduction  is  slow  and 
too  much  stannous  chloride  will  be  added  before  the  color  disappears. 

If  iron  is  suspected  in  the  residue,  before  the  final  addition  of  stannous 
chloride,  filter,  wash  twice  with  hot  water,  burn  the  filter  in  a  platinum 
crucible,  add  2  or  3  gms.  of  Na2C03  and  fuse.  Cool  and  dissolve  out  the 
soluble  salts  with  hot  water,  leaving  the  ferric  oxide  precipitated.  Filter 
out  the  ferric  oxide,  wash  it  from  the  filter  paper  with  a  jet  of  hot  water  f 
(Fig.  52),  dissolve  it  in  hydrochloric  acid  and  add  to  the  main  solution. 
Then  proceed  with  the  final  reduction  with  stannous  chloride. 

If  any  platinum  should  be  dissolved  and  should  pass  into  the  iron 
solution,  it  produces  when  stannous  chloride  is  added  a  yellow  color 
which  persists  after  the  iron  is  all  reduced.  The  complete  reduction 
of  the  iron  can  then  be  detected  only  by  testing  drops  of  the  solution 
with  a  reagent  such  as  potassium  sulphocyanate. 

Dilute  to  the  capacity  of  the  beaker  with  cold  water  and  add, 
quickly,  5  cc.  of  mercuric  chloride  solution;  stir  vigorously. 

SnCl2+2HgCl2  =SnCl4+2HgCl. 

The  excess  of  stannous  chloride  must  be  oxidized  before  titration. 
If  too  much  stannous  chloride  has  been  added,  or  if  the  solution  is  warm 
when  the  mercuric  chloride  is  added,  or  if  it  is  added  slowly,  part  of  the 

*  Mixer  and  Dubois.     Jour.  Am.  Chem.  Soc.,  17,  405. 
f  Eng.  and  Min.  Jour.,  96,  p.  695. 


IKON  IN  ORES— PERMANGANATE  METHOD 


61 


mercuric  chloride  will  be   reduced  to    metallic   mercury,  giving  a  gray 
color  to  the  precipitate  instead  of  the  pure  white  of  mercurous  chloride. 

2HgCl+SnCl2  =SnCl4+Hg2. 

The  presence  of  mercury  spoils  the  determination,  as  it  causes  a 
reduction  of  the  standard  solution.  The  determination  must  therefore 
be  discarded. 

Add  10  cc.  of  the  manganous  sulphate  and  phosphoric  acid 


FIG.  52. — Washing  a  Precipitate  from  the  Filter  Paper  to  a  Beaker. 

solution.      Stir  and   titrate  with   standard  permanganate  solu- 
tion. 

The  formation  of  brown  ferric  chloride  on  titration  would  render 
the  detection  of  the  end-point  difficult,  therefore,  phosphoric  acid  is 
added  in  sufficient  quantity  to  prevent  the  formation  of  ferric  chloride. 
Manganese  sulphate  prevents  the  reduction  of  the  permanganate  by  the 
hydrochloric  acid.* 

*  For  suggested  reasons  for  this  action  see  Tread  well-Hall,  "Analytical 
Chemistry,"  2,  482-3. 


62  METALLUKGICAL  ANALYSIS 

POTASSIUM  BICHROMATE  (PENNY'S)  METHOD  FOR  IRON  IN  ORES 

Outline.  The  iron  is  dissolved  from  the  ore  in  hydrochloric 
acid.  It  is  reduced  to  the  ferrous  condition  with  stannous 
chloride,  the  excess  of  stannous  chloride  oxidized  with  mer- 
curic chloride  and  the  quantity  of  the  iron  is  then  measured  by 
titrating  it  with  a  standard  solution  of  potassium  dichromate. 

Reagents. 

Stannous  chloride  solution.     (See  p.  59.) 

Mercuric  chloride  solution.     (See  p.  59.) 

Potassium  ferricyanide  solution.  Dissolve  a  small  crystal, 
not  more  than  10  mgm.,  of  KsFe(CN)6  in  25  cc.  of  water.  This 
must  be  made  fresh  just  before  using. 

Standard  solution  of  potassium  dichromate.  Dissolve  4.4 
gm.  K2Cr20r  in  1  liter  of  water.  One  cubic  centimeter  should 
be  equivalent  to  about  0.005  gm.  of  Fe.  Standardize  this  solu- 
tion against  an  ore,  iron  wire,  or  ferrous  ammonium  sulphate 
in  which  the  iron  has  been  accurately  determined.  If  ore  is 
used  for  standardizing,  take  0.5  gm.,  or  if  iron  wire,  weigh  about 
0.25  gm.  and  treat  it  by  the  process  for  ore  (p.  63).  If  ferrous 
ammonium  sulphate  is  used,  treat  it  as  follows: 

Standardization  of  Potassium  Dichromate  Solution.  Weigh 
accurately  about  0.5  gm.  of  FeSO4(NH4)2SO4  •  6H2O.  Dissolve  it 
in  10  cc.  of  water  and  5  cc.  of  hydrochloric  acid.  (See  note,  bot- 
tom of  p.  52.)  Heat  to  boiling  and  add  1  drop  of  stannous  chloride 
solution.  Cool  and  dilute  to  200  cc.  with  cold  water.  Add 
5  cc.  of  mercuric  chloride  solution.  Stir,  and  titrate  with  the 
potassium  dichromate  solution  until  a  blue  color  ceases  to  form 
when  a  drop  of  the  iron  solution  is  added  to  a  drop  of  potas- 
sium ferricyanide  solution  on. a  white  tile. 

Before  beginning  the  titration,  place  several  drops  of  the 
potassium  ferricyanide  solution  on  a  white  tile  or  plate,  then  as 
titration  proceeds,  take  out  a  drop  of  the  iron  solution  on  a  glass 
rod  and  add  it  to  a  drop  of  the  ferricyanide  solution;  a  blue 


IRON  IN  ORES— BICHROMATE  METHOD  63 

color  is  produced  as  long  as  any  iron  remains  unoxidized  in  the 
solution. 

The  first  test  that  fails  to  give  a  blue  color  indicates  that 
all  the  iron  is  oxidized  and  this  point  is  therefore  the  end-point. 
Read  the  burette  and  divide  the  weight  of  iron  in  the  salt  taken 
by  the  number  of  cubic  centimeters  used  in  the  titration  to  find 
the  value  of  1  cc.  of  the  solution  in  Fe. 

Fe  in  Ore.  Weigh  .5  gm.  of  ore  and  transfer  it  to  a  small 
porcelain  crucible. 

Heat  over  a  Bunsen  burner  for  a  few  minutes  at  low  redness 
to  destroy  carbonaceous  matter.  (See  notes  on  p.  59.) 

Place  the  crucible  with  the  ore  in  a  400-cc.  beaker. 

Add  10  cc.  of  hydrochloric  acid  and  4  cc.  of  stannous  chloride 
solution. 

Heat  to  dissolve  the  iron.  When  the  solution  begins  to  turn 
yellow  add  stannous  chloride  solution  drop  by  drop  to  reduce 
the  iron.  Finally,  when  all  the  iron  is  dissolved  from  the  ore 
and  the  volume  of  solution  has  been  reduced  by  evaporation 
to  about  10  cc.,  add  stannous  chloride  solution  drop  by  drop 
until  the  color  just  disappears,  then  add  one  drop  more. 

If  iron  is  suspected  in  the  residue,  before  the  final  addition  of  stan- 
nous chloride,  filter,  wash  twice  with  hot  water,  burn  the  filter  in  a 
platinum  crucible,  add  2  or  3  gms.  of  sodium  carbonate  and  fuse.  Cool 
and  dissolve  out  the  soluble  salts  with  hot  water,  leaving  the  ferric  oxide 
precipitated.  Filter  off  the  ferric  oxide,  wash  it  from  the  filter  paper 
with  a  jet  of  hot  water  (Fig.  52)  dissolve  it  in  hydrochloric  acid  and  add 
to  the  main  solution.  Then  proceed  with  the  final  reduction  with  stan- 
nous chloride. 

If  any  platinum  should  be  dissolved  and  should  pass  into  the  iron 
solution,  it  produces  when  stannous  chloride  is  added  a  yellow  color 
which  persists  after  the  iron  is  all  reduced.  The  complete  reduction 
of  the  iron  can  then  be  detected  only  by  testing  drops  of  the  solution 
with  a  reagent  such  as  potassium  sulphocyanate. 

Dilute  to  200  cc.  with  cold  water  and  add  quickly  5  cc. 
of  mercuric  chloride  solution.  Stir  vigorously  and  titrate  at 


64 


METALLURGICAL  ANALYSIS 


once  with  standard  potassium  dichromate  solution,  testing  a 
drop  of  the  iron  solution  occasionally  on  a  white  tile  with  a 
drop  of  potassium  ferricyanide  solution,  in  the  manner  described 
above  under  the  standardization  of  the  dichromate  solution, 
until  the  blue  color  is  no  longer  produced.  Read  the  burette 
and  calculate  the  percentage  of  iron  in  the  ore. 

6FeCl2+K2Cr207+14HCl=6FeCl3+2CrCl3+2KCH-7H20. 

The  iron  solution  becomes  green  as  titration  proceeds,  owing  to  the 
formation  of  chromic  chloride. 

When  ferrous  iron  is  added  to  a  solution  of  potassium  ferricyanide, 
Prussian,  or  Turnbull's,  blue  is  formed,  and  the  color  of  the  tests  becomes 
fainter  as  the  amount  of  ferrous  iron  diminishes. 

Fe'/Cl2+K3Fe'//(CN)6+2H2O=Fe"(CN)6KH2Fe///(OH),-h2KCL* 

DETERMINATION  OF  FERROUS  IRON 

By  the  foregoing  methods  the  total  iron  in  an  ore  is  deter- 
mined. It  is  sometimes  necessary  to 
determine  the  amount  of  iron  present 
in  the  ferrous  condition.  This  is  done 
by  dissolving  the  material  under  con- 
ditions that  are  neither  oxidizing  nor 
reducing,  and  titrating  the  ferrous  iron 
at  once. 

Reagents.  Carbon  dioxide.  This 
may  be  generated  in  a  Kipp  appa- 
ratus, or  in  a  flask  (Fig.  53)  provided 
with  a  separating  funnel  and  delivery 
tube.  Place  calcium  carbonate  (mar- 
ble or  limestone  fragments)  in  the  flask 
and  let  dilute  hydrochloric  acid  (1  :  3) 
drop  from  the  funnel  to  produce  the 
gas  at  the  desired  rate. 

*  Treadwell-Hall,  "  Analytical  Chemistry,"  Vol.  1,  p.  95.  Hofman,  Heine, 
and  Hochtlen,  Annalen,  337  (1904),  p.  1. 


FIG.  53. — Carbon  Dioxide 
Generator. 


DETERMINATION  OF  FERROUS  IRON        65 

Hydrochloric  acid  (1.2)  diluted  with  an  equal  volume  of 
water. 

"  Titrating  solution  "  of  manganese  sulphate  and  phosphoric 
acid.  (See  p.  59.) 

A  standard  solution  of  potassium  permanganate.     (See  p.  51.) 

Fe  in  the  Ferrous  Condition.  Weigh  0.5  gm.  of  ore  and 
transfer  it  to  a  250-cc.  Florence  flask.  Close  the  flask  with 
a  two-hole  stopper  provided  with  intake  and  delivery  tubes 
of  glass.  Let  the  delivery  tube  dip  under  water  in  a  beaker. 
Attach  the  intake  to  the  C02  generator  and  pass  the  gas  ten 
minutes  to  displace  the  air.  Disconnect  the  gas  generator 
and  attach  to  the  intake  a  funnel,  through  which  introduce 
30  cc.  of  dilute  hydrochloric  acid  (1  :  1).  Disconnect  the  funnel 
and  re-attach  the  gas  generator  to  the  intake  and  pass  carbon 
dioxide  through  the  flask.  While  the  gas  passes  through, 
gently  warm  the  flask  with  a  Bunsen  burner  until  the  ore 
is  dissolved  and  the  volume  has  been  reduced  by  evaporation 
to  15  cc.  Cool,  add  20  cc.  of  the  "  titrating  solution,"  and 
100  cc.  of  water,  and  titrate  with  standard  permanganate  solu- 
tion. 

For  FeO  and  Fe2Os.  If  the  iron  is  to  be  reported  as  oxides, 
subtract  the  weight  of  ferrous  iron  from  the  total  iron,  the  remain- 
der will,  of  course,  be  the  weight  of  trivalent,  or  ferric  iron,  in 
the  ore.  Multiply  the  weight  of  ferrous  iron  by  the  factor  1.2865 
to  obtain  the  corresponding  weight  of  ferrous  oxide,  and  the 
weight  of  ferric  iron  by  1.4298  for  the  weight  of  ferric  oxide. 
Then  divide  the  weight  of  each  of  these  oxides  by  the  weight  of 
ore  taken  to  find  the  percentage  of  each  present. 

Materials  which  will  not  completely  decompose  in  hydrochloric 
acid  may  be  treated  according  to  Cooke's  Method.* 

Weigh  0.5  gm.  of  the  ore  and  place  it  in  a  large  (80  cc.)  plat- 
inum crucible,  add  a  little  water  that  has  been  recently  boiled 
and  about  10  cc.  of  dilute  sulphuric  acid  (1  :  3).  Place  the 
*  Bull.  422,  U.  S.  Geolog.  Survey,  p.  168. 


66 


METALLURGICAL  ANALYSIS 


crucible  under  the   funnel  on  the  water  bath  (Fig.  54).     Start 

the  flow  of  CO2  and  of  water 
through  the  bath.  When  the  air 
under  the  funnel  has  been  re- 
placed by  CC>2  raise  the  funnel 
and  quickly  add  to  the  crucible 
about  6  cc.  of  strong  hydro- 
fluoric acid  and  replace  the  fun- 
nel. When  steam  issues  freely 
from  the  funnel  cut  off  the  sup- 
ply of  C02  and  continue  the 
boiling  for  one  hour  or  until  the 
ore  is  all  decomposed.  Turn  off 
the  heat  and  turn  on  the  COs 
and  the  water. 

Place  in  the  beaker  in  which 
the  titration  is  to  be  made  300 
cc.  of  cold  freshly  boiled  water 
and  10  cc.  of  sulphuric  acid. 
Now  wash  the  contents  of  the 
crucible  into  the  beaker  and 
titrate  with  standard  perman- 
ganate solution,  letting  the  solu- 
tion run  in  as  rapidly  as  possible 
with  continuous  stirring  until  the 
first  pink  blush  pervades  the 

whole  solution  and  persists  at  least  two  seconds.     If  much  iron 
or  much  hydrofluoric  acid  is  present  the  color  fades  rapidly. 

DETERMINATION  OF  FREE  METALLIC  IRON 

In  the  investigation  of  furnace  products  it  is  sometimes 
necessary  to  determine  the  quantity  of  iron  that  has  been  reduced 
to  the  metallic,  or  elementary  condition.  This  determination 
may  be  made  by  dissolving  the  iron  in  a  neutral  solution  of 


FIG.  54. — Cooke's  Apparatus  for 
Ferrous  Iron  Determination.  The 
water  bath  has  a  specially  made 
cover  with  circular  trough  in 
which  water  is  kept  to  make  an 
air-tight  joint  with  the  funnel 
which  is  turned  over  the  crucible. 


DETERMINATION  OF  FREE  METALLIC  IRON  67 

mercuric  chloride  under  an  atmosphere  of  carbon  dioxide,  and 
titrating  with  potassium  permanganate  solution;  or  by  dissolving 
in  dilute  hydrochloric  acid,  collecting  the  evolved  hydrogen  and 
measuring  it  in  a  gas  apparatus,  estimating  its  weight  and  its 
equivalent  in  iron.  In  case  iron  sulphide  is  present,  the  latter 
method  must  be  used,  and  the  hydrogen  sulphide  generated  must 
be  absorbed  by  passing  the  gas  through  a  solution  of  potassium 
hydroxide  or  other  absorbent  before  measuring  the  volume  of 
hydrogen.* 

Reagents.     Neutral  saturated  solution  of  mercuric  chloride. 

Solution  of  manganous  sulphate  and  phosphoric  acid  (titrat- 
ing mixture).  (See  p.  59.) 

Carbon  dioxide.     (See  p.  64.) 

Standard  solution  of  potassium  permanganate.     (See  p.  51.) 

Free  Metallic  Fe.  Weigh  0.5  gm.  of  the  sample.  Transfer  it 
to  a  300-cc.  flask.  Add  75  cc.  neutral  saturated  mercuric  chloride 
solution  and  close  the  flask  with  a  two-hole  rubber  stopper  pro- 
vided with  intake  and  delivery  tubes  of  glass.  Let  the  delivery 
tube  dip  under  water  in  a  beaker  as  a  seal.  Pass  carbon  dioxide 
to  displace  air  in  the  flask.  (See  p.  64  for  method  of  generating 
carbon  dioxide.)  Heat  to  just  below  boiling  and  hold  at 
this  temperature  for  half  an  hour  or  until  the  metallic  iron  is 
all  dissolved.  Cool  the  flask,  maintaining  within  it  an  atmosphere 

of  C02. 

Fe-f  2HgCl2  =  Hg2Cl2+FeCl2. 

When  cold,  filter  the  solution  through  asbestos  into  30  cc. 
of  "  titrating  mixture,"  wash  with  cold  water,  and  titrate  with 
standard  permanganate  solution. 

Ferrous  iron  may  be  determined  in  this  material  by  return- 
ing the  asbestos  with  residue  to  the  flask  and  proceeding  accord- 
ing to  the  method  given  on  page  64. 

*  These  methods  were  contributed  by  D.  A.  Lyon,  metallurgist  of  the 
U.  S.  Bureau  of  Mines,  in  whose  investigations  they  were  used  by  J.  F. 
Cullen  and  G.  A.  Reinhardt. 


68 


METALLURGICAL  ANALYSIS 


Free  Metallic  Iron  in  the  Presence  of  Titanium.  If  metallic 
titanium  or  iron  sulphide  is  present  it  is  advisable  to  determine 
the  metallic  iron  by  dissolving  the  sample  in  dilute  hydrochloric 
acid  and  measuring  the  hydrogen  evolved.  This  is  carried  out 

in  the  apparatus  shown  in  Fig. 
55.  From  the  reservoir  R,  acid 
is  delivered  to  the  test-tube  B 
through  the  tube  E.  At  C  the 
glass  tubing  is  connected  by  a 
rubber  tube  on  which  is  a  clamp. 
The  tube  E  passes  through  a 
two-hole  stopper  to  the  lowest 
point  in  the  bottom  of  the  test- 
tube  B,  and  is  here  drawn  to  a 
fine  capillary  opening.  The  test- 
tube  B  is  connected  by  a  capillary 
glass  tube  to  the  burette  at  D. 
The  leveling  tube  F  contains  a 

solution  of  sodium  hydroxide  (250  gms.  per  liter)  to  absorb  the 
hydrogen  sulphide  which  is  evolved  with  the  hydrogen.  Nearly 
fill  the  acid  reservoir  with  dilute  hydrochloric  acid  (1  :  1). 
Remove  the  test-tube  B  from  its  stopper  and,  by  blowing  at 
A,  force  the  acid  over  to  fill  the  tube  E.  Close  the  clamp  C 
and  wipe  dry  the  point  of  the  tube  E. 

Weigh  0.5  gm.  of  the  material  to  be  analyzed  and  transfer 
it  to  the  dry  test-tube.  Fit  the  test-tube  to  its  stopper.  Read 
the  burette.  Lower  the  leveling  tube  F,  release  the  clamp  at 
C,  and  draw  in  the  necessary  volume  of  acid  (2  ins.  or  so  in  depth), 
and  close  the  clamp  at  C.  Collect  the  evolved  hydrogen  in  the 
burette.  When  evolution  has  ceased,  warm  the  acid  in  the  test- 
tube  with  a  very  small  flame  for  a  few  minutes.  The  acid  will 
attack  metallic  titanium  if  the  heating  is  continued.  Pass  the  gas 
back  and  forth  from  the  burette  by  means  of  the  leveling  tube 
until  the  absorption  of  hydrogen  sulphide  is  complete  and  the 


FIG.  55, — Apparatus  Assembled  for 
the  Determination  of  Free  Me- 
tallic Iron. 


DETERMINATION  OF  SILICA  IN  ORE  69 

hydrogen  is  at  room  temperature.  Finally,  force  the  acid  in 
the  test-tube  back,  by  raising  the  leveling  tube,  until  it  just 
stands  at  the  fine  point  of  the  tube  E  (its  initial  position),  and 
read  the  burette.  The  increase  in  volume  is  due  to  the  hydro- 
gen; calculate  its  weight  from  the  barometer  and  thermometer 
readings. 

Fe+2HCl=FeCl2+H2. 

One  gram  of  hydrogen  is  equivalent  to  27.6488  gms.  of  iron. 
1  cc.  of  hydrogen  at  0°  C.  and  760  mm.  mercury  weighs  0.00008987 
gm. 

Suppose  the  volume  of  hydrogen  is  24.5  cc.  at  a  temperature 
of  18°  C.  and  a  pressure  of  740  mm.  At  0°  C.  and  760  mm. 
this  volume  would  become 

273X740X24.5     000^ 

(273+18)760   = 

.00008987X22.37  =  .00201041  gm.=wt.  of  the  hydrogen. 
27.6488 X. 0020104  =  .055585  gm.=  equivalent  in  iron. 

.055585X100 

— r—    —  =  11.11  per  cent  Fe  in  the  material. 


DETERMINATION  OF  SILICA  IN  ORE 

HYDROFLUORIC  ACID,  BERZELIUS  METHOD 

Outline.  The  ore  is  dissolved  in  hydrochloric  acid,  the 
solution  taken  to  dryness  and  the  residue  heated  to  dehydrate 
the  silica.  The  residue  is  treated  with  hydrochloric  acid,  filtered 
and  weighed.  The  silica  is  volatilized  with  hydrofluoric  acid, 
the  residue  weighed  and  deducted  from  the  weight  of  impure 
silica. 

Reagent.     Hydrofluoric  acid,  HF. 

SiO2  in  Ore.     Weigh  1  gm.  of  ore  (or  0.5  gm.,  if  high  in  silica) 


70 


METALLURGICAL  ANALYSIS 


and  transfer  it  to  a  casserole  or  beaker.     Add  20  cc.  of  hydrochloric 
acid,  cover  with  a  watch  glass,  and  heat  to  dissolve. 

M2Si03+2HCl  =  2MCl+H2Si03.     M  represents  bases  of  soluble  silicates. 

Evaporate  the  solution  to  dry  ness  and  hold  the  residue  at 
a  temperature  of  about  120°  C.  for  one  hour. 

H2Si03=Si02+H20. 
Do  not  heat  above  130°;  some  SiO  may  recombine  with  bases,  forming 


FIG.  56.— Freas  Electric 
Oven. 


FIG.  57. — Control  of  the  Temperature  of  an 
Air  Bath. 


soluble  silicates.  A  Freas  electric  oven  (Fig.  56)  is  excellent  for  main- 
taining a  constant  temperature,  but  it  is  not  difficult  to  adjust  the  heat 
under  the  air-bath,  if  a  thermometer  is  fixed  with  its  bulb  opposite  the 
bottom  of  the  beaker  (Fig.  57). 

Cool  and  add  10  cc.  of  hydrochloric  acid  and  10  cc.  of  hot 
water.  Heat  to  dissolve  soluble  salts,  dilute  with  a  little  hot 
water,  filter,  and  wash  (four  or  five  times)  with  hot  dilute 
hydrochloric  acid  (1:3)  until  the  8162  is  free  from  iron,  and  then 
wash  with  hot  water  to  remove  the  hydrochloric  acid. 


SILICA  IN  ORE  71 

If  washed  with  hot  water  before  all  the  iron  is  out,  basic  salts  of  iron 
may  be  precipitated  in  the  filter  when  the  free  acid  has  been  removed. 
(See  note  p.  52.) 

Place  the  filter  with  the  8162  in  a  weighed  platinum  crucible, 
carefully  raise  the  temperature  with  a  Bunsen  burner  and  burn 
off  the  filter  paper.  Then  heat  with  a  blast  lamp  five  minutes. 

A  high  heat  is  necessary  to  drive  off  the  last  traces  of  combined 
water. 

Cool  in  a  desiccator  and  weigh. 

Add  to  the  crucible  enough  hydrofluoric  acid  to  dissolve  the 
Si02  (5  cc.)  and  two  drops  of  sulphuric  acid. 


Take  care  not  to  breathe  the  fumes  of  hydrofluoric  acid,  as  they 
are  extremely  irritating;  neither  should  the  acid  be  allowed  to  touch  the 
skin. 

Evaporate  carefully  to  dryness  in  a  hood  with  a  good  draft. 
Ignite  with  the  blast  lamp,  cool  in  the  desiccator  and  weigh. 
The  loss  in  weight  represents  the  SiC>2. 

With  high  silica  ores  it  may  be  necessary  to  repeat  the  treatment 
with  hydrofluoric  and  sulphuric  acids  until  the  weight'  of  the  residue 
is  constant. 

Silicon  tetrafluoride  being  volatile  is  lost  on  evaporation.  Titanium 
fluoride  is  also  volatile;  therefore,  sulphuric  acid  is  added  to  retain 
titanium  in  the  crucible  as  sulphate  in  case  titanium  is  present.  The 
sulphates  of  iron,  aluminum,  and  titanium  are  broken  up  at  a  high 
temperature,  liberating  S03,  the  oxides  remaining  in  the  crucible. 

SILICA  IN  ORE 
FUSION  WITH  SODIUM  CARBONATE 

Outline.  The  ore  is  fused  with  a  flux,  dissolved  in  dilute 
hydrochloric  acid,  and  the  silica  is  dehydrated  by  evaporating 
the  solution  to  dryness.  The  residue  is  treated  with  hydro- 


72  METALLURGICAL  ANALYSIS 

chloric  acid,  and  the  silica  is  filtered  from  the  solution  and 
weighed. 

Reagents.     Sodium  carbonate,  Na2COs. 

Potassium  carbonate,  K^COa. 

SiO2  in  Ore.  Weigh  0.5  gm.  of  ore  and  transfer  it  to  a 
platinum  crucible.  Add  about  5  gms.  of  fused  sodium  carbonate. 

Put  on  the  cover  and  fuse  with  the  blast  lamp.  Direct  the 
flame  against  the  side  of  the  crucible  so  that  melting  will  begin 
at  the  top. 

If  heated  rapidly  at  the  bottom,  the  sudden  expulsion  of  C02  may 
throw  some  of  the  charge  from  the  crucible. 

Si02+Na2C03  =  Na2Si03+C02. 
The  fusion  should  be  complete  within  fifteen  or  twenty  minutes. 

Take  the  crucible  in  the  tongs  and  turn  it  so  that  the  fusion 
will  run  well  up  on  the  side.  Continue  turning  it  until  the 
fusion  freezes  in  a  thin  layer,  covering  as  much  of  the  inside  of 
the  crucible  as  possible.  When  the  crucible  is  cool,  place  it  on 
its  side  in  a  casserole  which  contains  nearly  enough  water  to 
cover  the  crucible,  also  put  the  crucible  cover  in  the  casserole. 
Cover  with  a  watch  glass  and  pour  down  the  lip  of  the  casserole 
hydrochloric  acid  to  make  the  solution  acid.  Warm  to  hasten 
solution,  and  as  the  fusion  dissolves  add  more  hydrochloric  acid 
to  keep  the  solution  always  distinctly  acid. 

Na,SiO,+2HCl  =2NaCl+H2Si03. 

Take  out  the  crucible  and  cover,  carefully  wash  them  off, 
and  let  the  washings  run  into  the  casserole.  Evaporate  the 
solution  in  the  casserole  to  dryness,  and  hold  at  a  temperature 
of  about  120°  for  an  hour.  Add  20  cc.  of  dilute  hydrochloric 
acid  (1  :  1),  warm  to  dissolve  the  soluble  salts,  dilute  with  20 
cc.  of  hot  water  and  filter.  Wash  several  times  with  warm 


DETERMINATION  OF  SULPHUR  IN   ORE  73 

dilute  hydrochloric  acid  (1:3)  and  finally  wiih  hot  water  to 
remove  all  hydrochloric  acid.  Burn  carefully  in  a  weighed 
platinum  crucible  over  a  Bunsen  burner,  ignite  at  the  highest 
temperature  of  the  blast  lamp  five  minutes,  cool  in  a  desiccator 
and  weigh.  Calculate  the  percentage  of  SiC>2. 

A  small  amount  of  silica  is  carried  through  with  the  filtrate.  For 
very  accurate  work  this  must  be  recovered  by  dehydration  a  second 
time.  Evaporate  the  filtrate  to  dryness,  take  up  the  residue  with  very 
dilute  hydrochloric  acid,  filter  and  burn  the  two  filters  together  before 
weighing.  For  other  notes  see  the  method  for  silica  pages  70  and  71. 

DETERMINATION  OF  SULPHUR  IN  ORE 

Outline.  The  ore  is  fused  with  a  flux,  the  fusion  treated 
with  hot  water  to  dissolve  sulphates,  the  residue  filtered  off, 
the  filtrate  acidified  with  hydrochloric  acid,  evaporated  to  dry- 
ness  and  the  silica  dehydrated.  The  residue  is  treated  with 
dilute  hydrochloric  acid  and  the  silica  is  filtered  out.  The 
sulphur  is  precipitated  from  the  filtrate  with  barium  chloride, 
filtered  and  weighed. 

Reagents.     Sodium  carbonate,  Na2COs. 

Sodium  nitrate,  NaNOs. 

Alcohol,  C2H60. 

Barium  chloride,  BaCfe,  10  per  cent  solution. 

S  in  Ore.  Fuse  1  gm.  (or  1.3738  gms.,  ten  times  the  factor) 
of  ore  with  8-10  gms.  of  sodium  carbonate  and  about  0.5  gm.  of 
sodium  nitrate  in  a  platinum  crucible. 

Sodium  nitrate  is  added  to  oxidize  sulphur  to  S03  and  is  preferred 
to  potassium  nitrate,  for  if  potassium  salts  are  present,  the  precipitate 
of  barium  sulphate  will  contain  potassium  sulphate.  Only  a  small 
amount  of  the  nitrate  should  be  added,  since  it  attacks  platinum.  (See 
p.  29.) 

If  the  fusion  is  made  with  a  gas  flame,  the  products  of  combustion 
which  contain  sulphur  must  not  be  permitted  to  enter  the  crucible. 
This  may  be  prevented  by  inclining  the  crucible  and  allowing  the  lower 


74 


METALLURGICAL  ANALYSIS 


part  to  project  through  a  hole  in  a  sheet  of  asbestos,  as  shown  in  the 
figure  (Fig.  58),*  or  a  spirit  lamp  may  be  used. 

Cool  the  fusion.  Treat  it  with  hot 
water  to  dissolve  soluble  silicates,  sulphates, 
etc.,  and  to  precipitate  the  iron  as  oxide. 

Barium  sulphate  when  precipitated  has  a 
tendency  to  carry  down  impurities  with  it,  some 
of  which  cannot  be  removed  by  washing.  If 
iron  is  present,  ferric  sulphate  comes  down  with 
the  barium  sulphate,  and  on  ignition  breaks  up 
into  ferric  oxide  and  S03,  the  latter  escaping. 
Other  trivalent  metals  also,  as  far  as  possible, 
should  be  removed. 

If  the  ore  contains  manganese  its  presence 
will  be  indicated  by  the  green  color  of  the 
fusion,  and  it  should  be  removed  by  the  addi- 
tion of  a  few  drops  of  alcohol,  which  precipitates 
it  from  the  sodium  manganate,  as  manganese 
dioxide.  Sodium  hydroxide  and  aldehyde  are 
also  produced  by  the  reaction. 

Mn02+Na2C03+0  =C02+Na2Mn04, 
Na2MnO4+C2H60  =2NaOH+Mn02+C2H40. 

Decant  the  solution  through  a  filter  and 
wash  twice  by  decantation.  Acidify  the  ni- 
trate with  hydrochloric  acid  and  evaporate 
the  solution  to  dryness. 


FIG.  58. — Arrangement 
of  Crucible  to  Pre- 
vent the  Products  of 
Combustion  of  the 
Gas  from  Contami- 
nating the  Fusion. 


If  nitric  or  chloric  acid  is  present,  the  barium  salts  of  these  acids 
will  be  precipitated  with  the  sulphate,  and  cannot  be  washed  out. 
These  acids  are  broken  up  by  evaporating  with  hydrochloric  acid. 
Silica,  also,  would  contaminate  the  precipitate  if  it  were  not  dehydrated 
and  removed. 

Cool;  add  a  few  drops  of  hydrochloric  acid  and  200  cc.  of 
hot  water. 


Lowe,  Zeit.  f.  Anal.  Chem.,  20  (1881),  p.  224. 


DETERMINATION  OF  PHOSPHORUS  IN  ORE      75 

Only  a  very  little  hydrochloric  acid  should  be  used,  as  barium 
sulphate  is  slightly  soluble  in  hydrochloric  acid. 

Filter  and  wash  well  with  hot  water.  Heat  the  filtrate  to 
boiling  and  add  boiling  barium  chloride  solution,  drop  by  drop, 
stirring  until  the  precipitation  of  barium  sulphate  is  complete. 
Then  add  10  cc.  more  of  barium  chloride  solution  and  let  the 
determination  stand  hot  (not  boiling)  half  an  hour  or  more. 

If  barium  chloride  solution  is  added  rapidly,  barium  chloride  comes 
down  with  the  sulphate.  (See  Precipitation,  p.  20.) 

Filter  and  wash  four  times  by  decantation.  Transfer  the 
precipitate  to  the  filter  and  wash  until  the  washings  are  free 
from  barium.  (Test  with  sulphuric  acid.) 

Burn  carefully  at  a  low  heat  with  a  Bunsen  burner.  Burn- 
ing filter  paper  reduces  some  barium  sulphate  to  the  sulphide; 
but,  if  air  is  admitted  and  the  heating  continued,  the  sulphide 
is  reoxidized. 

Cool  in  a  desiccator  and  weigh  the  BaSCU.  Calculate  the 
percentage  of  sulphur  according  to  the  method  given  on  page 
31.  If  the  factor  weight  of  ore  was  used,  the  weight  of  BaSO4 
multiplied  by  10  gives  the  percentage  of  sulphur  in  the  ore. 

DETERMINATION  OF  PHOSPHORUS  IN  ORE 

MOLT BD ATE  METHOD,  WEIGHING  THE  YELLOW  PRE- 
CIPITATE 

Outline.  The  ore  is  dissolved  in  hydrochloric  acid,  by  pre- 
vious fusion  if  necessary;  the  silica  dehydrated  and  filtered 
off;  the  hydrochloric  acid  in  the  filtrate  is  replaced  by  nitric 
acid  by  evaporation;  ammonia  is  added,  and  the  phosphorus 
is  precipitated  by  ammonium  molybdate,  filtered  in  a  Gooch 
crucible  and  weighed. 

Reagents.     Sodium  carbonate,  Na2COa,  fused. 

Dilute  nitric  acid,  HNO3  (2:3). 

Alcohol,  C2HeO  (95  per  cent). 


76  METALLURGICAL  ANALYSIS 

Molybdate  solution.  Dissolve  10  gms.  MoOs  in  40  cc.  of  cold 
water  and  8  cc.  of  ammonia.  Filter,  and  pour  this  solution  slowly 
into  dilute  nitric  acid  (40  cc.  nitric  acid  (1.42) +60  cc.  water). 
Stir  and  keep  the  solution  cool  to  prevent  the  precipitation 
of  molybdic  acid.  If  a  precipitate  begins  to  form,  stop  the 
addition  of  the  ammoniacal  solution,  cool  by  placing  the  beaker 
in  cold  water,  and  continue  agitation  until  the  precipitate  dis- 
solves. Add  about  0.05  gm.  of  microcosmic  salt  to  clear  the 
solution  of  suspended  impurities.  Shake,  let  the  solution  stand 
twenty-four  hours,  and  filter  or  decant  the  clear  solution  for  use. 

Wash  solution  of  ammonium  nitrate.  Add  to  10  cc.  of  nitric 
acid  (sp.gr.  1.42),  200  gms.  ammonium  nitrate,  and  water 
to  make  one  liter. 

P  in  Ore.  Weigh  1.63  gms.  of  ore  (100  times  the  factor) 
and  transfer  it  to  a  casserole. 

A  large  precipitate  of  ammonium  phosphomolybdate  is  not  easy  to 
wash  and  dry  for  weighing.  A  sufficient  quantity  of  ore  should  be 
taken  to  yield  from  0.2  gm.  to  0.4  gm.  of  the  precipitate.  Therefore 
1.63  gms.,  100  times  the  factor  weight,  is  a  convenient  quantity  to  take 
of  ores  containing  from  0.2  to  0.3  per  cent  phosphorus.  Of  ores  higher 
in  phosphorus,  1  gm.,  or  better,  50  times  the  factor  weight,  0.815  gm., 
should  be  taken;  of  ores  lower  in  phosphorus,  200  or  300  times  the  factor 
weight,  that  is,  3.26  gms.  or  4.89  gms.,  would  be  required. 

Add  30  cc.  of  hydrochloric  acid.  Digest  over  a  moderate 
heat  until  there  is  no  further  action  on  the  ore.  Dilute  with 
an  equal  volume  of  water  and  filter  into  a  casserole.  Evaporate 
the  filtrate  to  dryness,  and  while  the  evaporation  is  going  on, 
burn  the  filter  paper  with  the  residue  in  a  platinum  crucible, 
cool,  and  add  sodium  carbonate,  in  quantity  about  six  times  the 
weight  of  the  residue.  Fuse,  place  the  crucible  in  the  casserole 
in  which  the  ore  was  dissolved,  and  dissolve  the  fusion  in  hot 
water  acidulated  with  hydrochloric  acid. 

If  it  has  been  previously  determined  that  all  the  phosphorus  in 
the  ore  under  examination  is  soluble,  the  residue  need  not  be  fused, 


DETERMINATION  OF  PHOSPHORUS  IN  ORE      77 

but  may  be  discarded  after  filtering  and  washing.  In  this  case,  before 
filtering,  the  solution  should  be  taken  to  dryness,  the  residue  baked  to 
oxidize  phosphorus,  dissolved  in  a  little  hydrochloric  acid,  and  then 
diluted  with  water. 

Evaporate  this  solution  to  dryness  and  heat  the  residue  as 
well  as  that  from  the  filtrate,  at  about  200°  C.  for  half  an  hour, 
or  until  they  no  longer  yield  an  odor  of  hydrochloric  acid. 

Baking  of  these  residues  should  be  continued  until  the  carbonaceous 
matter  is  destroyed  and  the  phosphorus  is  oxidized  to  P04;  otherwise, 
all  the  phosphorus  will  not  be  precipitated. 

Cool  and  treat  each  of  the  residues  with  a  little  hydrochloric 
acid  to  dissolve  the  iron.  Dilute  with  an  equal  volume  of  hot 
water,  and  filter  both  into  a  small  Erlenmeyer  flask.  Wash 
well  with  hot  water.  Evaporate  the  combined  filtrate  until 
it  has  a  syrupy  consistency,  or  until  ferric  chloride  begins  to 
separate. 

The  washed  precipitate  may  be  burnt  and  weighed  in  the  usual 
manner  for  the  determination  of  Si02. 

Hydrochloric  acid  dissolves  the  yellow  precipitate  and  therefore 
must  be  removed  by  evaporating  with  nitric  acid. 

Add  30  cc.  of  nitric  acid  (sp.gr.  1.42)  and  evaporate  to  15  cc. 
Dilute  to  50  cc.  with  water.  Add  ammonia  until  all  the  iron 
is  precipitated  and  there  is  a  slight  excess  indicated  by  the  odor. 
Add  dilute  nitric  acid  (2:3),  a  few  drops  at  a  time,  shaking  until 
the  precipitate  is  just  dissolved,  then  add  about  5  cc.  more,  or 
enough  to  give  the  solution  an  amber  color. 

These  proportions  of  nitric  acid  and  ammonium  nitrate  in  the  solu- 
tion are  the  best  for  the  precipitation  of  the  phosphomolybdate. 

Heat  the  solution  to  80°  C.  and  add  60  cc.  of  molybdate  solu- 
tion. 

FeP04+12(NH4)2Mo04+24HNO3 

=  (NH4)3P04.12Mo03+21NH4N03+Fe(N03)3+12H20 


78 


METALLURGICAL  ANALYSIS 


A  high  temperature  hastens  the  precipitation,  but  if  heated  higher 
than  80°  C.  there  is  danger  of  bringing  down  molybdic  acid  with  the 
yellow  precipitate. 

Shake  five  minutes,  let  settle  one  hour,  and  filter  in  a  Gooch 
crucible;  or  shake  ten  minutes  and  filter  at  once.  The  solution 

should  be  shaken  violently,  by 
hand,  shaking  machine  (Fig.  59), 
mechanical  stirrer  (see  Fig.  23, 
p.  22,  and  Fig.  60,  p.  98),  or  by 
a  jet  of  compressed  air. 

Wash  five  times  with  the  wash 
solution  of  ammonium  nitrate; 
then  wash  twice  with  alcohol. 
Dry  one  hour  in  an  air  bath  at 
about  130°  C.,  cool  in  a  desic- 
cator, and  weigh.  If  100  times 
the  factor  weight  (1.63  gms.)  has 
been  used,  the  weight  of  the 
yellow  precipitate  will  represent 
the  percentage  of  phosphorus  in 
the  ore:  if  any  multiple  of  that 
weight  is  used,  divide  the  weight  of  the  yellow  precipitate  by  the 
multiple.  (See  p.  32.) 

The  compound  (NH4)sP04-12Mo03  contains  theoretically  1.653 
per  cent  phosphorus,  but  the  precipitate  formed  according  to  this  method 
has  been  found  by  repeated  tests  to  contain  1.63  per  cent  phosphorus. 

Phosphorus  from  the  Filtrate  from  SiO?.  Phosphorus  and 
silica  may  be  determined  in  the  same  sample.  Weigh  the  sample 
of  ore  and  proceed  with  the  determination  of  silica  (p.  71)  until 
the  silica  has  been  filtered  from  the  solution.  Evaporate  the 
filtrate  until  solids  begin  to  separate.  Add  30  cc.  of  nitric  acid 
(1.42),  evaporate  to  15  cc.  and  complete  the  determination  in 
the  manner  described  in  the  preceding  method  (p.  77)  If  the 


FIG.  59.— Camp's  Shaking  Machine. 


PHOSPHORUS  IN  ORE  79 

weight  of  ore  used  was  not  a  factor  weight  for  phosphorus, 
calculate  the  percentage  of  phosphorus  in  the  manner  described 
on  page  31. 

PHOSPHORUS  IN  ORE 

WEIGHING  AS 


If  the  yellow  precipitate  is  always  formed  under  the  same  con- 
ditions, its  composition  is  constant  and  the  method  in  which 
the  yellow  precipitate  is  weighed  is  a  very  exact  one  for  the 
determination  of  phosphorus;  but,  since  the  conditions  of  pre- 
cipitation are  not  always  uniform,  it  is  better,  for  very  exact 
work,  to  dissolve  the  yellow  precipitate,  reprecipitate  the  phos- 
phorus with  magnesia  mixture,  and  weigh  as  Mg2P207. 

Reagents.  Magnesia  mixture:  Dissolve  55  gms.  MgC^  •  GEbO 
and  70  gms.  NH4C1  in  650  cc.  of  water  and  dilute  the  solution  to 
one  liter  with  ammonia  (sp.gr.  .96). 

Also  the  reagents  required  for  the  method  on  page  75. 

P  in  Ore,  Weigh  2.7873  gms.  ore  (10  times  the  factor)  and 
proceed  according  to  the  method  on  page  76  until  the  yellow 
precipitate  is  ready  to  be  filtered.  Filter  on  a  9-cm.  filter  paper 
and  wash  five  times  with  the  ammonium  nitrate  wash  solution. 
Place  a  clean  beaker  under  the  funnel,  pierce  the  filter  paper  and 
wash  the  precipitate  through  with  a  fine  jet  of  hot  water.  Drop 
a  little  ammonia  on  the  filter  and  wash  with  hot  water.  If  any 
precipitate  sticks  to  the  flask  in  which  it  was  formed,  dissolve 
it  out  with  a  few  drops  of  ammonia  mixed  with  a  little  water  and 
add  the  solution  to  that  in  the  beaker.  Keep  the  volume  small 
(not  greater  than  50  cc.).  Stir  and,  if  the  precipitate  does 
not  all  dissolve,  add  a  little  more  ammonia. 

(NH4)3PO4-  12Mo03+24NH4OH  =  12(NH4)2Mo04H-(NH4)3P04+12H20. 

Add   hydrochloric   acid   to   neutralize   the   solution   and   if  the 
yellow  precipitate  begins  to  form,  add  ammonia  to  dissolve  it. 


80  METALLURGICAL  ANALYSIS 

If  a  white  precipitate  remains  insoluble  in  ammonia,  filter 
it  out.  Add  hydrochloric  acid  to  slight  acidity  and  then  10 
cc.  of  magnesia  mixture.  Add  ammonia  drop  by  drop,  stirring 
constantly,  until  the  solution  is  neutral.  Note  the  depth  of 
the  solution  in  the  beaker  and  add  ammonia  until  the  volume 
is  increased  by  one-third.  Stir  and  let  the  solution  stand  four 
hours. 


Filter  and  wash  with  dilute  ammonia.  Dry  the  precipitate. 
Separate  the  precipitate  from  the  filter  paper.  (See  Fig.  31.) 
Burn  the  paper  on  a  platinum  wire,  letting  the  ash  fall  into  a 
crucible;  add  the  precipitate  to  the  crucible  and  heat  to  low 
redness  over  a  Bunsen  burner  until  the  precipitate  is  white. 
Then  heat  with  a  blast  lamp  ten  minutes. 

2MgNH4P04  =  Mg2P207+2NH3+H2O. 

The  temperature  must  not  be  raised  until  the  precipitate  is  white. 
If  the  filter  paper  is  burned  in  contact  with  the  precipitate  some  phos- 
phorus may  be  reduced  and  attack  the  platinum. 

Cool  in  a  desiccator  and  weigh.  The  weight  of  Mg2?2O7 
multiplied  by  10  expresses  the  percentage  of  P  in  the  ore. 

PHOSPHORUS  IN  ORE 

EMMERTON'S  VOLUMETRIC  METHOD 

Outline.  The  ore  is  dissolved,  the  phosphorus  precipitated 
as  ammonium  phosphomolybdate  and  filtered.  The  precipitate 
is  dissolved  in  ammonium  hydrate,  the  molybdic  acid  reduced 
with  zinc  and  titrated  with  standard  potassium  permanganate 
solution,  the  quantity  of  phosphorus  being  measured  indirectly. 

Reagents.     Sodium  carbonate.    Na2COs; 

Dilute  nitric  acid  (2:3); 

Dilute  sulphuric  acid',  25  cc.  of  sulphuric  acid  (1.84)  diluted 
to  one  liter  with  water. 


PHOSPHORUS  IN   ORE  81 

Standard  solution  of  KMnO4;  2.83  gms.  of  KMn04  dissolved 
in  water  and  the  solution  diluted  to  one  liter.  This  solution 
may  be  standardized  by  taking  a  definite  weight  of  a  phosphate 
in  which  the  percentage  of  phosphorus  is  known,  dissolving 
and  precipitating  the  phosphorus  as  ammonium  phosphomolyb- 
date,  filtering  and  dissolving  the  yellow  precipitate  in  ammonia, 
reducing  and  titrating  exactly  as  given  below  in  the  method  for 
ore;  or  the  permanganate  solution  may  be  standardized  against 
iron  as  directed  on  page  51.  When  the  value  in  iron  has  been 
determined  multiply  the  value  by  0.88163,  the  ratio  of  molybdic 
acid  to  iron,  and  the  product  by  0.01794,  the  ratio  of  phosphorus 
to  molybdic  acid;  the  result  will  be  the  value  of  1  cc.  of  the 
permanganate  solution  in  terms  of  phosphorus.  Since  the  ratio 
of  phosphorus  to  molybdic  acid  in  the  yellow  precipitate  is 
not  constant  under  varying  conditions  of  formation,  great  care 
should  always  be  taken  to  produce  the  yellow  precipitate  under 
as  nearly  the  same  conditions  as  possible. 

Molybdate  solution.     (See  p.  76.) 

Wash  solution  of  acid  ammonium  sulphate:  to  one  liter  of 
water  add  16  cc.  of  ammonia  (sp.gr.  0.90)  and  25  cc.  sulphuric 
acid  (sp.gr.  1.84). 

A  reductor  charged  with  amalgamated  zinc.  (See  pp.  57  and 
58.) 

P  in  Ore.  Weigh  3  gms.  of  ore  (or  a  factor  weight)  and 
proceed  according  to  the  method  on  page  76  until  the  yellow 
precipitate  has  been  formed.  Filter  on  a  9-cm.  filter  paper  and 
wash  with  acid  ammonium  sulphate  solution  until  2  or  3  cc.  of 
the  wash  water  do  not  give  a  brown  color  on  the  addition 
of  a  drop  of  ammonium  sulphide. 

The  precipitate  must  be  washed  free  from  molybdic  acid  because 
the  phosphorus  is  measured  indirectly  by  titrating  back  to  molybdic 
acid  the  molybdenum  oxide  which  has  been  reduced  from  the  yellow 
precipitate. 

Pour  5  cc.  of  ammonia  and  20  cc.  of  water  into  the  flask  in 


82  METALLURGICAL  ANALYSIS 

which  the  precipitate  was  formed  to  dissolve  any  adhering 
precipitate,  and  then  pour  this  solution  on  the  precipitate  in 
the  filter,  letting  the  filtrate  to  run  into  a  250-cc.  beaker. 

(NH4)3P04-  12Mo03+24NH4OH  =  12(NH4)2MoO4+(NH4)3P04+12H20. 

Rinse  the  flask  into  the  beaker  and  wash  the  filter  with  water 
until  the  solution  in  the  beaker  measures  about  60  cc.  Add  10 
cc.  of  sulphuric  acid  (1.84)  and  pass  the  solution  through  the 
reductor,  after  having  passed  through  100  cc.  of  warm  dilute 
sulphuric  acid  (25  cc.  sulphuric  acid  (1.84)  in  1  liter). 

The  equation  2Mo03+3H2  =Mo203+3H20  expresses  the  complete 
reduction  of  MoOa  to  molybdic  oxide,  but  reduction  is  not  complete 
when  the  solution  passes  through  the  reductor  in  the  manner  here 
described.  Emmerton  gives  Moi20i9  as  the  form  he  obtained,  and 
Blair  and  Whitfield  give  Mo24037  as  the  product  of  the  method  as  carried 
out  by  them.  It  is  evident,  therefore,  that  the  operator  must  always 
carry  on  the  reduction  in  the  same  manner  and  under  the  same  con- 
ditions. 

Then  follow  with  200  cc.  of  the  same  dilute  sulphuric  acid 
in  the  manner  described  on  page  58,  being  careful  to  keep  the  end 
of  the  small  tube  of  the  reductor  below  the  surface  of  the  solu- 
tion in  the  flask  to  prevent  reoxidation.  Remove  the  flask  from 
the  reductor,  washing  into  it  from  the  reductor  any  adhering 
solution.  Titrate  with  standard  permanganate  solution. 

The  solution,  after  passing  through  the  reductor,  should  be  bright 
green  in  color;  if  brown  it  is  not  sufficiently  reduced  and  must  be 
discarded.  In  titrating  with  permanganate,  the  solution  of  the  yellow 
precipitate  changes  in  color  from  green  through  brown  and  pinkish 
yellow  to  colorless.  When  the  solution  becomes  colorless,  add  the 
permanganate  solution,  drop  by  drop — shaking — until  a  pink  color  is 
produced,  which  lasts  for  one  minute. 

Subtract  from  the  reading  of  the  burette  the  amount  given 
by  a  blank  determination  in  which  the  same  quantities  of  reagents 
are  used  as  in  the  regular  process.  (See  p.  58.)  Multiply  the  value 
of  1  cc.  in  phosphorus  by  the  number  of  cubic  centimeters  thus 


PHOSPHORUS   IN  ORE  83 

obtained.  Divide  this  product  by  the  weight  of  ore  taken  and 
multiply  the  result  by  100.  (See  p.  31.) 

Reduction  with  Powdered  Zinc.  Instead  of  reducing  the 
molybdic  acid  by  means  of  the  reductor,  reduction  may  be  effected 
by  adding  powdered  zinc  to  the  solution  of  yellow  precipitate. 
This  operation  is  best  carried  out  by  returning  the  solution  of 
the  yellow  precipitate  to  the  flask  in  which  the  precipitate  was 
formed  and  washing  the  filter  until  the  volume  of  solution  is 
about  75  cc.  Then  add  5  gms.  of  powdered  zinc  (through  100- 
mesh)  and  15  cc.  of  sulphuric  acid  (sp.gr.  1.84).  Close  the 
flask  at  once  with  a  rubber  stopper  carrying  a  delivery  tube 
which  dips  into  a  beaker  containing  a  saturated  solution  of  sodium 
bicarbonate.  After  standing  thirty  minutes  the  zinc  should  be 
in  solution  and  the  molydbic  acid  reduced,  when  it  is  ready  to 
be  titrated  with  standard  permanganate  solution.  A  blank 
should  be  run  at  the  same  time  and  the  necessary  correction 
made  for  all  determinations. 

When  this  method  of  reduction  is  used,  the  factor  express- 
ing the  ratio  of  molybdic  acid  to  iron  is  0.85714  instead  of 
0.88163,  there  being  this  difference  in  the  degree  of  reduction 
of  the  molybdic  acid  by  the  two  methods. 

PHOSPHORUS  IN  ORE 

PEMBERTON'S  ALKALI-METRIC  METHOD 

Outline.  By  this  method  the  ore  is  treated  in  the  manner 
described  on  page  76  to  the  formation  of  the  yellow  precipitate. 
After  the  yellow  precipitate  is  filtered  off  it  is  washed  to  free  it 
from  acids,  and  its  phosphorus  content  measured  indirectly  by 
titrating  with  an  alkali. 

Reagents.  Wash  solution  of  riMc  add;  13  cc.  nitric  acid 
(sp.gr.  1.42)  in  1  liter  of  water. 

Wash  solution  of  potassium  nitrate.  Dissolve  1  gin.  KNOs 
in  1  liter  of  water. 


84  METALLURGICAL  ANALYSIS 

Phenolphthalein  solution.  Dissolve  1  gm.  of  C2oHi404  in 
500  cc.  alcohol,  C2H6O  (95  per  cent). 

Standard  solution  of  sodium  hydroxide.  Add  to  100  gm. 
of  pure  NaOH  an  amount  of  water  just  insufficient  to  dissolve 
it  completely.  Let  it  settle  in  a  tall,  covered  vessel.  Most  of 
the  sodium  carbonate  which  is  present  as  an  impurity  remains 
undissolved.  Add  one  drop  of  a  solution  of  barium  hydroxide 
to  precipitate  CO2.  If  a  precipitate  forms  add  another  drop 
and  repeat  until  a  precipitate  ceases  to  form.  Withdraw  17 
cc.  of  the  solution  with  pipette  and  dilute  to  1  liter.  This  solu- 
tion must  be  protected  from  the  C02  of  the  air. 

Standard  nitric  acid.  Twenty-one  cubic  centimeters  of  nitric 
acid  (sp.gr.  1.42)  diluted  to  1  liter. 

These  standard  solutions  must  be  tested  against  each  other 
and  the  stronger  one  diluted  until  they  are  of  equal  strength, 
as  follows: 

With  the  pipette  take  out  20  cc.  of  the  sodium  hydroxide 
solution,  dilute  it  with  60  cc.  of  water,  add  3  drops  of  phenol- 
phthalein  solution  and  titrate  with  the  standard  nitric  acid  until 
the  pink  color  just  disappears. 

Phenolphthalein  is  red  with  alkalies  and  colorless  with  acids.  It 
is  a  weak  acid  and  is  very  slightly  dissociated  in  acid  solutions.  Accord- 
ing to  Ostwald's  theory  it  is  colorless  when  undissociated,  but  when 
combined  with  alkali  hydroxide,  the  salt  is  dissociated,  revealing  the 
red  color  of  the  cation.* 

If  the  solutions  are  not  of  equal  strength  dilute  the  stronger 
and  test  again. 

Suppose  19.4  cc.  of  nitric  acid  solution  were  required  to 
neutralize  20  cc.  of  sodium  hydroxide  solution;  then  the  volume 

*  Ostwald,  "  Foundations  of  Analytical  Chemistry,"  124.  For  another 
explanation  of  this  reaction  see  Stieglitz,  Jour.  Amer.  Chem.  Soc.,  25,  1112. 
Kober  and  Marshall,  Eighth  International  Congress  of  Applied  Chemistry, 
6,  157. 


PHOSPHORUS  IN  ORE  85 

of  nitric  acid  solution  remaining  must  be  increased  according  to 
the  ratio  19.4  :  20. 

19.4  :  20  =  vol.  nitric  acid  remaining  to  be  diluted:  final  vol. 
nitric  acid. 

The  difference  between  the  third  and  fourth  terms  repre- 
sents the  amount  of  water  to  be  added. 

Standardization  of  the  Sodium  Hydroxide  Solution.  When 
the  solutions  are  of  equal  strength  the  sodium  hydroxide  solu- 
tion is  standardized  by  weighing  2  gms.  of  an  ore  in  which 
the  phosphorus  has  been  previously  determined,  and  carrying 
it  through  the  process  as  given  below.  The  weight  of  phos- 
phorus being  known  and  the  number  of  cubic  centimeters  of  sodium 
hydroxide  solution  required  to  complete  the  reaction  below 
having  been  determined,  the  value  of  1  cc.  of  the  solution  is  given 
by  dividing  the  weight  of  phosphorus  by  the  number  of  cubic 
centimeters  of  sodium  hydroxide  solution  required  for  the 
reaction. 

2(NH4)SP04  •  12MoO,+46NaOH 

=  2(NH4)2HP04+(NH4)2Mo04+23Na2Mo04+22H20. 

Instead  of  using  a  standard  ore,  yellow  precipitate  may  be 
used.  This  is  prepared  from  a  phosphate  in  the  manner  described 
for  its  precipitation  from  a  solution  of  an  ore,  and  carefully 
dried  at  150°  C.  Weigh  about  0.2  gm.  of  yellow  precipitate, 
add  standard  sodium  hydroxide  solution,  10  cc.  at  a  time,  until 
the  precipitate  is  dissolved.  Dilute  with  50  cc.  of  water.  Add 
3  drops  of  phenolphthalein  solution  and  titrate  with  the  standard 
nitric  acid.  The  volume  of  nitric  acid  used,  deducted  from 
the  volume  of  sodium  hydroxide  solution,  leaves  the  number 
of  cubic  centimeters  of  sodium  hydroxide  solution  required  to 
neutralize  the  yellow  precipitate.  Multiply  the  weight  of 
yellow  precipitate  by  the  factor  for  phosphorus,  0.0163,  and 
divide  this  by  the  number  of  cubic  centimeters  of  sodium 
hydroxide  solution  used. 


86  METALLURGICAL  ANALYSIS 

P  in  Ore.  Weigh  2  gms.  of  ore  and  proceed  exactly  in  the 
manner  described  on  page  76  until  the  yellow  precipitate  has 
formed  and  settled.  Filter  on  a  9-cm.  filter  paper  and  wash 
5  times  with  1  per  cent  solution  of  nitric  acid,  then  wash 
with  potassium  nitrate  solution  until  the  acid  has  all  been 
removed.  Place  the  filter  paper  and  its  contents  in  the  flask 
in  which  the  precipitate  was  made  and  add  to  the  flask  standard 
sodium  hydroxide  solution,  20  cc.  at  a  time,  with  the  pipette, 
shaking  to  disintegrate  the  filter,  until  the  yellow  precipitate  is 
all  dissolved.  Dilute  with  50  cc.  of  water,  add  3  drops  of  phenol- 
phthalein  solution,  and  titrate  the  excess  of  alkali  with  the 
standard  nitric  acid.  Take  the  difference  between  the  number  of 
cubic  centimeters  of  nitric  acid  used  in  the  titration  and  the  total 
volume  of  sodium  hydroxide  solution  added  and  multiply  the 
result  by  the  value  of  1  cc.  in  phosphorus. 

PHOSPHORUS  IN  THE  PRESENCE  OF  TITANIUM 

Weigh  2  gms.  (or  a  factor  weight)  of  ore,  add  30  cc.  of 
hydrochloric  acid  and  heat  to  dissolve  as  much  of  the  ore  as 
possible.  Evaporate  the  solution  to  dryness  and  bake.  (See 
p.  70.)  Add  25  cc.  of  hydrochloric  acid  and  25  cc.  of  water. 
Heat  to  dissolve  the  iron,  and  filter. 

If  titanium  is  present,  when  the  residue  is  washed  with  water,  the 
filtrate  often  runs  through  turbid.  This  can  be  avoided  by  washing 
with  dilute  nitric  acid,  or  better,  with  an  acid  solution  of  ammonium 
nitrate  (p.  76).  The  filtrate  contains  the  greater  part  of  the  phos- 
phoric acid,  but  a  considerable  part  may  remain  with  the  residue. 

Treatment  of  the  Residue.  Fuse  the  residue  with  sodium  car- 
bonate and  extract  with  water. 

Sodium  phosphate  and  silicate  go  into  solution  and  sodium  titanate 
remains  insoluble. 

Filter,  acidify  the  filtrate  with  nitric  acid,  evaporate  the 
solution  to  dryness,  and  bake  at  120°  C.  Cool,  moisten  the  residue 


ALUMINA  IN  ORE  87 

with  nitric  acid,  and  add  water  to  dissolve  all  except  silica. 
Filter  from  the  silica.  Concentrate  the  nitrate  to  small  bulk 
by  evaporation,  nearly  neutralize  with  ammonia,  and  precipitate 
the  phosphorus  with  ammonium  molybdate. 

Treatment  of  the  Filtrate.  Evaporate  the  filtrate  until 
solids  begin  to  separate;  then  add  nitric  acid  and  proceed 
according  to  the  method  on  page  77,  until  the  yellow  precipitate 
is  filtered  and  washed.  This  yellow  precipitate,  and  that 
obtained  from  the  insoluble  residue,  are  dissolved  in  ammonia 
according  to  the  method  on  page  81.  If  the  solution  runs  through 
turbid,  and  a  gelatinous  residue  remains  on  the  filter,  heat  the 
'solution  for  some  time  and  filter.  Treat  both  these  residues 
with  nitric  acid  and  precipitate  the  phosphorus  from  the  result- 
ing solution  with  ammonium  molybdate.  Filter  out  this 
yellow  precipitate,  dissolve  it  in  ammonia,  and  add  it  to  the 
main  solution.  The  phosphorus  may  now  be  determined  by 
either  precipitating  with  magnesia  mixture  (p.  79),  or  by 
adding  sulphuric  acid,  reducing  and  titrating  by  Emmerton's 
method  (p.  80). 

ALUMINA  IN  ORE 

PHOSPHATE  METHOD 

Reagents.  Ammonium  phosphate  solution.  Dissolve  100 
gms.  of  (NH4)3PO4  in  1  liter  of  water. 

Sodium  thiosulphate  solution.  Dissolve  200  gms.  Na2S20s 
in  water  and  dilute  to  1  liter. 

Acetic  acid,  CH3CO-OH,  80  per  cent. 

Ammonium  acetate.  Dissolve  200  gms.  CHsCO-ONH^  in 
water  and  dilute  to  1  liter. 

AkOs  in  Ore.  Weigh  1  gm.  of  ore  and  proceed  according 
to  the  method  for  silica  (p.  71)  until  the  silica  has  been  filtered 
off  and  washed.  Cool  the  filtrate  and  dilute  it  to  about  400  cc.; 
add  30  cc.  of  ammonium  phosphate  solution,  and  then  add  ammo- 
nia until  a  faint  permanent  precipitate  is  formed.  Add  1.5  cc. 


88  METALLURGICAL  ANALYSIS 

of  strong    hydrochloric    acid.     Stir  until  the  precipitate  is  dis- 
solved and  add  50  cc.  of  sodium  thiosulphate  solution. 

2FeCl3+2Na2S203=2NaCl+2FeCl2+Na2S406. 

The  aluminum  is  precipitated  as  the  neutral  phosphate  from  a  boil- 
ing solution  faintly  acid  with  acetic  acid,  and  it  comes  down  free  from 
iron,  if  the  iron  has  been  reduced  with  sodium  thiosulphate. 

Heat  just  to  the  boiling-point  and  add  8  cc.  of  acetic  acid 
mixed  with  15  cc.  of  ammonium  acetate  solution  and  boil  ten 
minutes.  Let  the  precipitate  settle  a  few  minutes,  filter  as 
rapidly  as  possible,  and  wash  ten  times  with  hot  water.  Ignite 
the  filter  and  its  contents  at  a  low  temperature  until  the  carbon 
is  destroyed,  and  then  at  the  highest  temperature  of  the  muffle 
furnace  or  the  blast  lamp.  Cool  and  weigh  as  A1PO4,  multiply 
by  0.4184,  the  factor  for  A12O3. 

MANGANESE  IN  ORE 
VOLHARD'S  METHOD 

Outline.  The  ore  is  dissolved  in  hydrochloric  and  nitric 
acids.  These  acids  are  replaced  with  sulphuric.  The  solution 
is  diluted  and  nearly  neutralized  with  sodium  carbonate.  An 
excess  of  zinc  oxide  is  added  and  the  solution  is  titrated  hot  with 
standard  potassium  permanganate  solution. 

Reagents.  Emulsion  of  pure  zinc  oxide.  ZnO  shaken  with 
a  sufficient  amount  of  water  to  form  an  emulsion. 

Saturated  solution  of  crystallized  sodium  carbonate, 

Na2C03-10H20. 

Standard  potassium  permanganate  solution.  (See  p.  51.) 
This  solution  may  be  made  of  such  strength  that  1  cc.  equals 
0.1  per  cent  manganese  for  the  quantity  of  ore  taken.  It  is 
standardized  against  an  iron  ore  in  which'  the  percentage  of 
manganese  is  known.  Or  it  may  be  standardized  against  iron 


MANGANESE  IN  ORE  89 

in  the  usual  way  and  its  value  in  manganese  calculated  from 
the  following  reactions. 

6MnS04+4KMn04+5ZnS04+  14H20 

=4KHS04+7H2S04+5Zn(HMn03)2. 

10FeS04+2KMn04+8H2S04  =  5Fe(S04)3+2MnS04+K2S04+8H20. 

The  first  reaction  is  that  upon  which  this  method  depends; 
the  second  is  the  familiar  reaction  of  potassium  permanganate 
with  iron. 

It  will  be  observed  that  two  molecules  of  potassium  perman- 
ganate oxidize  10  atoms  of  iron  in  the  one  case,  and  3  atoms  of 
manganese  in  the  other.  The  value  of  the  solution  in  man- 
ganese, therefore,  may  be  calculated  from  its  value  in  iron  by 

3(54  93) 
multiplying  the  value  in  iron  by  the  factor         ,!      .  =0.2951. 

lU^tDO.OTry 

Mn  in  Ore.  Treat  1  gm.  of  ore  in  a  casserole  with  15  cc. 
of  hydrochloric  acid.  Add  5  cc.  of  nitric  acid  to  oxidize  the 
iron.  Heat  to  complete  the  decomposition.  Add  25  cc.  of 
water  and  5  cc.  of  sulphuric  acid.  Evaporate  until  the  sul- 
phuric acid  begins  to  fume.  Cool,  dilute  to  150  cc.  with  water 
and  heat  to  dissolve  sulphates. 

If  it  is  suspected  that  any  manganese  remains  undissolved, 
filter  and  burn  the  residue  in  a  platinum  crucible.  Treat  the 
residue  with  a  little  hydrofluoric  acid  (1  cc.)  and  a  few  drops  of 
sulphuric  acid  and  evaporate  to  sulphuric  acid  fumes.  Dilute 
the  solution  in  the  crucible  and  add  it  to  the  main  solution. 

Nearly  neutralize  the  sulphate  solution  with  a  solution  of 
sodium  carbonate.  Transfer  it  to  a  500-cc.  graduated  flask 
and  dilute  with  water  to  the  graduation.  Mix  well,  take  out 
50  cc.  with  the  pipette  and  let  it  run  into  a  small  Erlenmeyer 
flask.  Add  50  cc.  (an  excess)  of  zinc  oxide  and  titrate  with 
potassium  permanganate  solution. 

A  sufficient  quantity  of  zinc  oxide  is  added  to  neutralize  the  solution, 
precipitate  the  iron,  and  provide  an  excess  which  will  keep  the  solu- 


90  METALLURGICAL  ANALYSIS 

tion  neutral  as  titration  goes  on.  Sulphuric  acid  is  formed  by  the  reac- 
tion, and  the  solution  should  be  kept  neutral  for  the  reaction  to  proceed 
according  to  the  equation  given  above. 

Keep  the  solution  hot  while  titrating,  but  do  not  let  it  boil. 
After  each  addition  of  permanganate,  shake  vigorously  and  let 
the  precipitate  settle.  If  kept  hot  it  settles  readily  and  the 
pink  end-point  can  be  detected  in  the  layer  of  clear  solution 
above  the  precipitate. 

The  result  obtained  by  this  titration  must  be  multiplied  by 
10,  since  only  0.1  of  the  whole  was  titrated. 

MANGANESE  IN  ORE 
TITRATION  WITH  SODIUM  ARSENITE 

Outline.  The  hydrochloric  acid  in  which  the  ore  is  dissolved 
is  displaced  by  sulphuric.  The  solution  is  then  diluted  and  the 
manganese  is  oxidized  to  permanganic  acid  by  adding  ammonium 
persulphate  and  silver  nitrate.  The  silver  is  then  precipitated 
with  sodium  chloride  and  the  solution  titrated  with  a  standard 
solution  of  sodium  arsenite. 

Reagents.    Dilute  sulphuric  acid  (1  :  1). 

Ammonium  persulphate,  (NH^H^Og. 

Solution  of  silver  nitrate.  Dissolve  66.66  gms.  AgNOs  in  one 
liter  of  water.  Dilute  20  cc.  of  this  solution  to  1  liter  for  use. 
Each  15  cc.  contains  0.02  gm.  AgN03. 

Standard  solution  of  sodium  arsenite.  A  stock  solution  is 
made  by  dissolving  30  gms.  sodium  carbonate  in  water,  adding 
10  gms.  of  arsenious  acid,  boiling  until  the  acid  is  in  solution, 
and  diluting  to  1  liter.  Dilute  about  125  cc.  of  the  stock  solution 
to  2000  cc.  and  standardize  this  solution  against  a  steel  or  an 
ore  in  which  the  manganese  has  been  previously  determined. 

Sodium  chloride,  0.2  per  cent  solution.  Dissolve  2  gms. 
NaCl  in  water  and  dilute  the  solution  to  1  liter. 

Mn  in  Ore.     Weigh  1  gm.  of  ore  and  transfer  it  to  a  casserole 


MANGANESE  IN  ORE  91 

or  beaker.  Add  25  cc.  of  hydrochloric  acid  and  5  cc.  of  sulphuric 
acid.  Heat  until  the  sulphuric  acid  fumes.  Cool,  add  25  cc. 
of  water  and  heat  until  the  salts  are  dissolved. 

If  the  insoluble  residue  is  suspected  of  containing  manganese,  filter 
and  burn  the  residue  in  a  platinum  crucible.  Add  2  or  3  drops  of  dilute 
sulphuric  acid  (1:1)  and  about  5  cc.  of  hydrofluoric  acid.  Evapo- 
rate until  the  sulphuric  acid  fumes.  Add  5  cc.  of  the  dilute  sulphuric 
acid  (1  :  1).  Warm  until  the  residue  is  in  solution  and  add  it  to  the 
main  solution. 

Transfer  the  solution  to  a  50-cc.  graduated  flask.  Dilute  to 
the  mark  and  mix.  With  a  pipette  transfer  10  cc.  of  the  solu- 
tion to  a  1 50-cc.  Erlenmeyer  flask.  Add  15  cc.  of  the  silver 
nitrate  solution  and  about  1  gm.  of  moist  ammonium  persulphate; 
heat  over  -a  flame  or  water  bath  until  the  pink  color  of  per- 
manganic acid  appears. 

2MnS044-4(NH4)2S208+8HzO=2H2Mn04+4(NH4)2S04H-6H2S04. 

The  silver  nitrate  is  a  catalytic  agent  and  hastens  the  above  reaction.* 
The  reaction  takes  place  equally  well  in  nitric  acid  or  sulphuric 
acid  or  a  mixture  of  the  two.     It  is  essential  to  have  a  sufficient  amount 
of  silver  nitrate  present. 

While  the  permanganic  acid  is  forming  remove  the  flask  from 
the  heat  and  place  it  in  a  cold  water  bath.  When  cool,  dilute 
to  about  100  cc.,  add  7  cc.  of  sodium  chloride  solution,  and  titrate 
with  sodium  arsenite  solution  until  the  pink  color  is  discharged. 

If  the  silver  is  not  precipitated  with  sodium  chloride,  the  manganese 
is  reoxidized,  and  the  end-point  is  not  permanent. 

Since  a  standard  solution  of  sodium  arsenite  sometimes  changes 
in  strength  suddenly  and  unexpectedly,  some  chemists  prefer  to  titrate 
with  a  standard  solution  of  ammonium  ferrous  sulphate  instead.  See 
sodium  bismuthate  method,  p.  92. 

*  Marshall,  Proc.,  Royal  Soc.  Edin.,  1900,  p.  225. 


92  METALLURGICAL  ANALYSIS 

MANGANESE  IN  ORE 
COLOR  METHOD 

Treat  1  gm.  of  ore  in  the  manner  described  in  the  preceding 
method  until  it  is  dissolved  and  the  solution  is  diluted  to  50 
cc.  in  a  graduated  flask.  Mix  and  pour  the  solution  through 
a  dry  filter  paper.  With  the  pipette  transfer  10  cc.  to  an  8-in. 
test-tube,  1  in.  in  diameter.  Add  15  cc.  of  silver  nitrate  solution 
and  about  1  gm.  of  ammonium  persulphate.  Heat  in  a  water 
bath  and  when  the  color  of  permanganic  acid  appears,  remove 
the  test-tube  from  the  heat  and  place  it  in  a  cold  water  bath. 
Compare  this  solution  in  a  colorimeter  (see  p.  44)  with  a  similar 
solution  prepared  in  exactly  the  same  way  from  a  standard 
ore  in  which  the  manganese  is  known.  Instead  of  a  standard 
ore  a  standard  steel  may  be  used,  in  which  case  dissolve  0.2 
gm.  of  the  steel  in  10  cc.  of  nitric  acid  (sp.gr.  1.2),  add  15  cc. 
of  the  silver  nitrate  solution,  and  1  gm.  of  ammonium  persul- 
phate, and  proceed  according  to  the  method  given  above. 

MANGANESE  IN  ORE 

SODIUM  BISMUTHATE  METHOD 

Outline.  The  ore  is  decomposed  with  hydrofluric  and  sul- 
phuric acids.  After  the  hydrofluoric  acid  has  been  removed 
by  evaporation,  dilute  nitric  acid  is  added,  the  solution  cooled 
and  the  manganese  oxidized  to  permanganic  acid  with  sodium 
bismuthate.  The  excess  of  sodium  bismuthate  is  filtered  off, 
a  measured  volume  of  standard  ferrous  sulphate  solution  added 
to  the  filtrate  and  the  excess  of  ferrous  sulphate  titrated  with 
standard  potassium  permanganate  solution. 

Reagents.     Hydrofluoric  add,  HF. 

Dilute  nitric  add,  (1  :  3)  (sp.gr.  1.135). 

Dilute  nitric  add,  dilute  30  cc.  HNO3  (sp.gr.  1.42)  to  1  liter 
with  water. 


MANGANESE  IN  ORE  93 

Sodium  bismuthate,  NaBiOs. 

Standard  potassium  permanganate  solution,  1  gm.  KMn04 
to  the  liter.  After  this  solution  has  been  made  according  to 
the  method  given  on  page  51,  determine  the  exact  amount  of 
manganese  it  contains  per  cc.  by  standardizing  it  against  iron 
in  the  usual  way.  From  its  iron  value  calculate  the  weight  of 
manganese  in  each  cubic  centimeter  of  the  permanganate  solution 
using  the  following  equation: 

10  Fe  :  2Mn  =  value  in  Fe  per  cubic  centi- 
meter :  weight  of  Mn  per  cubic  centimeter. 

Ferrous  sulphate,  25.5  gms.  FeS04-7H2O  to  the  liter.  It 
is.  convenient  to  have  this  solution  of  such  strength  that  1  cc.  is 
equivalent  to  0.1  per  cent  manganese. 

The  value  of  the  ferrous  sulphate  solution  in  terms  of  the 
permanganate  solution  is  determined  as  follows: 

Measure  into  a  250-cc.  Erlenmeyer  flask  50  cc.  of  cold  nitric 
acid  (sp.gr.  1.13).  Add  about  0.5  gm.  of  sodium  bismuthate. 
Agitate  and  filter  through  asbestos.  Wash  the  filter  with  50  cc. 
of  cold  3  per  cent  solution  of  nitric  acid.  Add  50  cc.  of  ferrous 
sulphate  solution  and  titrate  with  potassium  permanganate  solu- 
tion to  a  pink  color. 

Mn  in  Ore.  Treat  1  gm.  of  ore  (if  the  ore  contains  more 
than  2  per  cent  manganese  use  0.5  gm.)  in  a  platinum  crucible 
with  4  cc.  of  strong  sulphuric  acid,  10  cc.  of  water,  and  10-20 
cc.  of  hydrofluoric  acid.  Evaporate  until  the  sulphuric  acid 
fumes  freely.  Cool  and  dissolve  in  25  cc.  of  dilute  nitric  acid 
(1:3).  Transfer  the  solution  to  a  200-cc.  Erlenmeyer  flask, 
using  25  cc.  of  nitric  acid  (1  :  3)  to  rinse  the  crucible.  Cool 
and  add  2  or  3  gms.  of  sodium  bismuthate,  and  agitate  the  con- 
tents of  the  flask  for  several  minutes. 

Sodium  bismuthate  in  the  presence  of  an  excess  of  nitric  acid  oxidizes 
the  manganese  to  permanganic  acid.  The  permanganic  acid  is  stable  in 


94  METALLURGICAL  ANALYSIS 

nitric  acid  of  1.135  sp.gr.  if  the  solution  is  cold;  if  hot  the  excess  of  the 
bismuth  salt  is  decomposed  and  tha  nitric  acid  then  reacts  with  the  per- 
manganic acid. 

Dilute  the  solution  with  50  cc.  of  3  per  cent  nitric  acid  and 
filter  through  asbestos  into  a  300-cc.  Erlenmeyer  flask.  Wash 
the  asbestos  with  50  to  100  cc.  of  cold  3  per  cent  nitric  acid. 
Run  into  the  solution  in  the  Erlenmeyer  flask  50  cc.  of  standard 
ferrous  sulphate  solution  from  a  pipette.  If  the  permanganate 
color  is  not  discharged,  add  more  ferrous  sulphate  solution, 
accurately  measured,  until  the  color  is  discharged.  Then  titrate 
back  to  pink  color  with  standard  permanganate  solution.  Having 
thus  determined  the  number  of  cubic  centimeters  of  ferrous 
sulphate  solution  required  to  react  with  the  manganese  in  the 
sample,  and  knowing  its  value  per  cubic  centimeter  in  man- 
ganese, calculate  the  percentage  of  manganese  in  the  sample. 

For  example,  suppose  24  cc.  of  ferrous  sulphate  solution  are 
equivalent  to  100  cc.  of  potassium  permanganate  solution,  and 
in  the  determination  50  cc.  of  ferrous  sulphate  solution  are 
added  to  the  solution  and  the  excess  titrated  back  with  25  cc. 
of  potassium  permanganate  solution;  44  cc.  of  the  ferrous  sul- 
phate solution  were,  therefore,  required  to  react  with  the  man- 
ganese in  the  sample,  and  this  number  is  to  be  multiplied  by 
its  value  in  manganese. 

In  addition  to  the  method  of  standardizing  given  above  under 
reagents,  after  the  solutions  have  been  tested  against  each  other,  the 
ferrous  sulphate  solution  may  be  standardized  by  taking  an  ore  in 
which  the  manganese  has  been  previously  determined,  and  running 
it  according  to  the  above  process. 

Instead  of  titrating  with  ferrous  sulphate,  a  standard  solution  of 
arsenious  acid  may  be  used.  (See  p.  90.) 


MANGANESE  IN  ORE  95 

MANGANESE  IN  ORE 
JULIAN'S  METHOD 

Outline.  The  ore  is  decomposed  with  hydrochloric  acid  and 
the  solution  taken  nearly  to  dryness.  Nitric  acid  is  added,  the 
solution  boiled  and  the  manganese  is  oxidized  to  manganese 
dioxide  by  adding  potassium  chlorate.  After  the  solution  is 
cooled  and  diluted  a  measured  volume  of  standard  solution  of 
hydrogen  peroxide  is  added  and  the  excess  of  peroxide  is  titrated 
with  standard  potassium  permanganate  solution. 

Reagents.    Hydrofluoric  add,  HF. 

Potassium  chlorate,  KClOa. 

Standard  potassium  permanganate  solution,  1.7375  gms.  KMnCU 
per  liter. 

Hydrogen  peroxide.  Dilute  1  Ib.  of  hydrogen  peroxide  with 
about  500  cc.  of  water,  add  200  cc.  of  sulphuric  acid  (sp.gr.  1.84), 
and  dilute  the  solution  to  9000  cc.  with  water. 

Determine  the  relative  values  of  these  two  solutions  as  follows : 

Boil  60  cc.  of  strong  nitric  acid  for  about  five  minutes.  Cool 
and  dilute  it  to  about  300  cc.  with  cold  water.  Add  to  the 
cold  solution  50  cc.  of  the  hydrogen  peroxide  solution  and  titrate 
it  with  the  standard  permanganate  solution. 

The  hydrogen  peroxide  solution  is  standardized  by  weighing 
a  sample  of  ore  in  which  the  manganese  has  been  previously 
determined  and  treating  it  according  to  the  method  given 
below. 

Mn  in  Ore.  Weigh  1  gm.  of  ore  and  transfer  it  to  a  beaker. 
Add  20  to  30  cc.  of  strong  hydrochloric  acid  and  heat  to  dissolve 
the  manganese.  If  the  insoluble  residue  is  suspected  of  contain- 
ing manganese,  add  a  few  drops  of  hydrofluoric  acid  and  evaporate 
the  solution  almost  to  dryness. 

Manganese-free  glass  must  be  used  if  hydrofluoric  acid  is  em- 
ployed. 


96  METALLURGICAL  ANALYSIS 

Add  75  cc.  of  strong  nitric  acid.  Boil  until  clear.  Add 
potassium  chlorate,  a  little  at  a  time,  until  green  chlorine  fumes 
cease  to  come  off.  Then  add  another  crystal  of  potassium  chlor- 
ate and  boil  five  minutes. 

5Mn(N03)2+2KC103+4H20=5Mn02+2KN03+8HN03+Cl2.* 

Cool  the  solution,  dilute  it  to  about  300  cc.  with  cold  water 
and  add  with  the  pipette  50  cc.  of  hydrogen  peroxide  solution. 

Mn02+H202+2HN03=Mn(N03)2-f2H20+02. 

After  the  manganese  dioxide  has  dissolved  determine  the  excess 
of  hydrogen  peroxide  by  titrating  with  standard  permanganate 
solution. 

5H202+2KMn04+6HN03=2KN03+2Mn(N03)2+8H20+502. 

The  equivalent  in  hydrogen  peroxide  solution  of  potassium 
permanganate  used  in  titration  is  deducted  from  the  total  volume 
of  hydrogen  peroxide  solution  added  and  the  remainder  which 
represents  the  quantity  of  hydrogen  peroxide  that  reacted  with 
manganese  dioxide  is  multiplied  by  its  value  per  cubic  centimeter 
in  manganese. 

LIME  IN  ORE 

Outline.  The  ore  is  decomposed  by  fusion  with  a  flux.  After 
dissolving  the  fusion  in  hydrochloric  acid,  the  silica  is  dehy- 
drated and  filtered  from  the  solution.  The  iron  and  aluminum 
are  then  precipitated  from  the  filtrate  with  ammonia,  and  filtered. 
The  calcium  is  then  precipitated  from  the  filtrate  with  ammonium 
oxalate,  filtered,  burnt  to  CaO  and  weighed. 

Reagent.  Ammonium  oxalate  solution.  Dissolve  40  gms. 
(NH4)2C2O4+H2O  in  a  liter  of  water. 

CaO  in  Ore.     Weigh  1  gm.  of  ore,  transfer  it  to  a  platinum 

*  Julian,  "  Quantitative  Analysis,"  236. 


MAGNESIA  IN  ORE  97 

crucible,  and  proceed  according  to  the  method  for  silica  (p.  71) 
until  the  silica  has  been  filtered  from  the  solution.  Make  the 
nitrate  alkaline  with  ammonia  to  precipitate  the  hydrates  of 
iron  and  aluminum.  Boil  off  the  excess  of  ammonia. 

Aluminum  hydrate  is  somewhat  soluble  in  ammonia. 
Let  the  precipitate  settle,  filter,  and  wash. 

The  precipitate  may  be  used  for  the  determination  of  iron  or 
aluminum. 

Acidulate  the  filtrate  with  hydrochloric  acid  and  evaporate 
it  down  to  150  cc.  Add  10  cc.  of  ammonia  and  5  cc.  of  ammonium 
oxalate  solution.  Boil  until  the  calcium  oxalate  precipitate 
is  formed.  Let  the  beaker  stand  in  a  warm  place  until  the 
precipitate  settles.  Filter  and  wash  with  hot  water. 

Before  filtering  add  a  few  drops  of  the  precipitant  to  the  clear 
supernatant  solution  to  test  for  unprecipitated  calcium. 
See  also  the  method  of  precipitation  given  on  page  162. 
Retain  the  filtrate  for  the  determination  of  magnesia. 

Burn  the  precipitate  in  a  platinum  crucible,  cool,  and  weigh 
as  CaO. 

For  the  method  of  titrating  calcium  oxalate  and  for  the  reac- 
tions see  the  method  for  lime  in  limestone,  pages  163  and  164. 

MAGNESIA  IN  ORE 

Reagent.  Solution  of  ammonium  phosphate.  Dissolve  100 
gms.  (NH4)2HPO4  in  1  liter  of  water. 

MgO  in  Ores.  Acidulate  with  hydrochloric  acid  the  filtrate 
from  the  calcium  oxalate;  see  the  method  above  for  lime.  Add 
5  cc.  of  ammonium  phosphate  solution  and  reduce  the  volume 
by  evaporation  to  200  cc.  Cool  the  solution,  stir  the  cool 
solution  with  a  stirring  machine  (Fig.  60),  and  add  25  cc.  of 


98 


METALLURGICAL  ANALYSIS 


ammonia,  drop  by  drop. 


FIG.  60. — Mechanical  Stirrer 
Driven  by  a  Jet  of  Com- 
pressed Air. 


Stir  continuously  for  one  hour,  let  settle, 
and  filter;  or,  if  possible,  let  stand 
over  night  before  filtering.  Wash  the 
precipitate  thoroughly  with  dilute 
ammonia  (1  :  4).  Dry,  and  separate 
the  precipitate  from  the  filter  paper. 
(See  Fig.  31.)  Heat  the  precipitate 
in  a  crucible  with  a  Bunsen  burner 
at  a  low  red  heat  until  the  precipi- 
tate is  white.  Burn  the  filter  paper 
on  a  platinum  wire  and  let  the  ash 
fall  into  the  crucible.  After  the  car- 
bon has  all  been  burnt  and  the  precipi- 
tate is  white,  heat  for  a  few  minutes 
at  a  high  temperature  with  the  blast 
lamp.  Cool  in  the  desiccator  and 
weigh  the  Mg2P2O7.  The  factor  for 
MgO  is  0.3621. 


For  notes  and  precautions,  see  the  method  for  magnesia  in  limestone 
page  165. 

TITANIUM  IN  ORE 

Outline.  The  ore  is  decomposed  with  potassium  pyrosulphate 
and  sulphuric  acid,  v the  solution  diluted,  and  the  silica  filtered 
from  it.  The  filtrate  is  nearly  neutralized  with  ammonia,  sodium 
sulphite  added  to  reduce  the  iron,  and  the  titanium  precipitated 
by  boiling  after  adding  acetic  acid  and  sodium  acetate.  The 
impure  metatitanic  acid  is  filtered  and  purified  by  decompos- 
ing it  and  repeating  the  process.* 

Reagents.     Potassium  pyrosulphate,  K2S207. 

Sodium    sulphite.     Dissolve  20  gms.  Na2S03-f  7H2O  in  100 

*  Gooch,  Chem.  News,  p,  55.  Drown,  Trans.  Amer.  Inst.  of  Min.  Eng., 
10,  p.  137. 


TITANIUM  IN  ORE  99 

cc.  of  water  and  add  sulphuric  acid  to  render  the  solution  dis- 
tinctly acid. 

Acetic  acid,  C2-H4O2. 

Sodium  acetate,  NaC2H302+3H2O. 

Sodium  carbonate,  fused  Na2COs. 

TiO2  in  Ore.  Weigh  1  gm.  of  very  finely  pulverized  ore  and 
mix  it  with  15  gms.  of  potassium  pyrosulphate  in  a  large  platinum 
crucible.  Heat  gently  to  melt,  and  raise  the  temperature  grad- 
ually to  a  low  red  heat  and  keep  the  mass  in  quiet  fusion  thirty 
minutes. 

Too  high  a  temperature  drives  off  sulphuric  acid  and  spoils  the 
fusion. 

Cool  and  add  about  20  cc.  of  strong  sulphuric  acid.  Heat 
until  the  contents  of  the  crucible  are  perfectly  liquid;  then 
cool. 

If  a  sufficient  amount  of  acid  was  added  the  fusion  remains  liquid 
after  cooling. 

Pour  the  solution  into  400  cc.  of  cold  water  in  a  600-cc.  beaker. 
Rinse  off  the  crucible  and  stir  the  solution  until  only  silica  remains 
undissolved.  Filter,  and  to  the  filtrate  add  ammonia  carefully, 
until  the  precipitate  dissolves  slowly  on  stirring.  Warm  and 
add  sodium  sulphite  solution  slowly,  a  little  at  a  time,  until  the 
color,  at  first  produced,  entirely  disappears. 

Fe2(S04)3+Na2S03+H20=2FeS04+Na2S04+H2S04. 

Do  not  heat  to  boiling,  as  titanium  oxide  in  that  case  would  sep- 
ite  as  a  milky  precipitate  and  render  it  difficult  to  determine  when  the 
luction  is  complete. 

If  the  precipitate  forms  and  the  solution  becomes  turbid,  add  a 
few  drops  of  hydrochloric  acid  to  clear  it  and  continue  the  addition 
)f  the  sulphite  solution,  giving  plenty  of  time  for  the  reaction  to  take 


100  METALLURGICAL  ANALYSIS 

After  the  addition  of  about  50  cc.  of  the  sulphite  solution 
the  titanium  solution  should  be  colorless  and  have  a  strong 
odor  of  sulphur  dioxide.  If  the  color  persists,  the  ferric  salts  are 
not  all  reduced.  Continue  the  addition  of  the  sulphite  solution 
and  warm  until  the  color  disappears.  Add  50  cc.  of  acetic  acid 
and  20  gms.  of  sodium  acetate  and  boil  vigorously  three  minutes. 

Ti(S04)2+4NaC2H302+3H20=2Na2S04-h4HC2H302+TiO(OH)2. 

Let  the  precipitate  of  impure  metatitanic  acid  settle,  filter,  and 
wash  with  hot  water.  Place  the  filter  with  residue  in  a  platinum 
crucible,  burn  off  the  filter  paper,  and  weigh  the  impure  titanium 
oxide.  Add  to  the  titanium  oxide  ten  times  its  weight  of  sodium 
carbonate  and  fuse.  Boil  the  fusion  with  water  until  it  is  dis- 
integrated. Filter  and  wash.  Wash  the  residue  off  the  filter 
into  a  beaker.  Let  the  precipitate  settle  and  decant  the  clear 
liquid  back  through  the  filter.  Dissolve  the  remaining  titanium 
precipitate  adhering  to  the  filter  paper  with  a  little  hydrochloric 
acid,  letting  it  run  through  the  paper  to  the  residue  in  the 
beaker.  Burn  the  filter  paper  at  a  low  heat  and  add  the  ash 
to  the  beaker.  Dissolve  the  contents  of  the  beaker  in  hydro- 
chloric acid,  then  add  10  cc.  of  dilute  sulphuric  acid  and  evap- 
orate until  the  sulphuric  acid  just  begins  to  fume.  Cool  and 
dilute  with  25  cc.  of  water.  Boil,  filter,  and  wash.  Dilute 
the  filtrate  to  250  cc.,  nearly  neutralize  it  with  ammonia,  and 
add  to  it  about  20  cc.  of  sodium  sulphite  solution  to  reduce 
the  remaining  traces  of  iron.  Add  30  cc.  of  acetic  acid  and 
10  gms.  of  sodium  acetate.  Stir  and  let  the  precipitate  of  meta- 
titanic acid  settle,  filter,  wash  with  hot  water,  burn,  and  weigh 
as  Ti02. 

TITANIUM  IN  ORE 
WELLER'S  METHOD 

Outline.  The  ore  is  fused  with  potassium  pyrosulphate, 
treated  with  sulphuric  acid  and  dissolved  in  water.  The  solu- 
tion is  filtered  and  diluted  to  a  definite  volume  in  a  graduated 


TITANIUM  IN  ORE    ,   '  101 

flask;  an  aliquot  part  is  taken  out  and  treated  with  hydrogen 
peroxide,  which  gives  it  a  yellow  color,  the  intensity  of  which 
depends  upon  the  quantity  of  titanium  present.  This  is  com- 
pared with  a  standard  solution  in  which  the  titanium  is  known.* 

Reagents.  Hydrogen  peroxide,  3  per*  cent  solution  free  from 
hydrofluoric  acid. 

Potassium  pyrosulphate,  K^^O?. 

Dilute  sulphuric  acid,  (3  :  100). 

Standard  solution  of  titanium  sulphate.  Weigh  0.6  gm.  of 
potassium  titanic  fluoride  which  has  been  recrystallized  several 
times  in  a  platinum  crucible  with  a  little  water  and  concentrated 
sulphuric  acid,  the  excess  of  acid  having  been  expelled  by  gentle 
ignition.  Dissolve  in  a  little  concentrated  sulphuric  acid  and 
add  dilute  sulphuric  acid  (3  :  100)  to  make  the  volume  100  cc. 
One  cubic  centimeter  of  this  solution  corresponds  to  0.002  gm. 
of  TiO2. 

This  solution  may  also  be  prepared  by  igniting  pure  Ti02 
at  a  dull  red  heat  to  a  constant  weight,  melting  cautiously 
with  potassium  bisulphate  until  Ti(>2  dissolves  and  the  fusion 
becomes  clear.  Cool  and  dilute  the  solution  to  a  definite  vol- 
ume with  dilute  sulphuric  acid  (3  :  100).  Then,  with  the 
pipette,  take  out  20  cc.  and  determine  the  Ti02  by  the  gravimetric 
method  given  on  page  99  and  dilute  the  remaining  solution 
with  weak  sulphuric  acid  solution  (3  :  100)  until  1  cc.  contains 
1  mg.  of  Ti02. 

Standard  solution  of  ferric  sulphate.  Prepare  a  dilute  solu- 
tion of  Fe2 (804)3  in  dilute  sulphuric  acid  and  determine  its  value 
per  cubic  centimeter  in  iron  by  means  of  standard  permanganate 
solution.  The  ferric  sulphate  solution  may  be  prepared  from 
ferrous  sulphate  by  dissolving  the  ferrous  sulphate  in  dilute 
sulphuric  acid  and  oxidizing  it  at  the  boiling-point  with  nitric 
acid  according  to  the  method  given  on  page  53,  evaporating 

*  Berichte,  15,  p.  2593.  Hillebrand,  Jour.  Amer.  Chem.  Soc.,  1895, 
p.  718. 


102  METALLURGICAL  ANALYSIS 

the  solution  until  sulphuric  acid  fumes  are  evolved  and  diluting 
with  water. 

TiO2  in  Ore.  Weigh  0.5  gm.  of  ore  and  fuse  it  with  5  gms. 
of  potassium  pyrosulphate  in  a  platinum  crucible  at  a  red  heat 
for  at  least  ten  minutes.  Cool,  add  5  cc.  of  sulphuric  acid,  melt 
again,  cool,  and  put  the  crucible  with  its  contents  in  a  beaker 
containing  200  cc.  of  water  and  5  cc.  of  sulphuric  acid.  Warm 
to  about  90°  C.  and  stir  to  dissolve  all  that  is  soluble.  Filter 
into  a  250-cc.  graduated  flask  and  dilute  the  solution  to  the 
graduation  with  sulphuric  acid  solution  (3  :  100). 

Measure  with  a  pipette  50  cc.  of  the  titanium  solution  and 
transfer  it  to  one  of  a  pair  of  Nessler  or  other  colorimetric  tubes. 
In  the  other  tube  place  that  quantity  of  ferric  sulphate  solution 
which  contains  as  much  iron  as  there  is  in  the  solution  of  ore 
in  the  first  tube. 

Since  the  iron  gives  a  slight  color  to  the  solution  it  is  necessary  to 
have  an  equal  quantity  in  each  tube. 

Dilute  the  ferric  sulphate  solution  in  the  second  tube  to  50  cc. 
with  dilute  sulphuric  acid  (3  :  100).  Add  to  each  tube  5  cc.  of 
hydrogen  peroxide. 

Hydrogen  peroxide  added  to  a  sulphuric  acid  solution  of  titanium 
produces  a  strong  yellow  color,  the  intensity  of  which  depends  on  the 
amount  of  titanium  present,  and  is  independent  of  the  excess  of  hydro- 
gen peroxide.  The  change  of  color  is  much  more  sensitive  with  small 
amounts  of  titanium.  Therefore  the  method  is  suitable  only  for 
materials  low  in  titanium.  If  the  titanium  is  high,  the  gravimetric 
method  may  be  used;  or  the  sulphate  solution  of  titanium  may  be 
diluted  to  a  large  volume  in  a  graduated  flask  and  a  suitably  small 
portion  withdrawn  for  the  colorimetric  determination. 

Now  run  into  the  second  tube  from  a  burette,  standard  titanium 
solution  until  the  color  produced  is  the  same  as  that  in  the  first 
tube.  The  quantity  of  titanium  in  the  volume  of  standard 
solution  added  to  the  second  tube  is  equal  to  that  in  the  solution 
of  ore  in  the  first  tube,  which  represents  one-fifth  of  the  sample. 


ANALYSIS  OF  IRON  AND  STEEL  103 

Instead  of  Nessler  tubes,  Eggertz  tubes  or  a  colorimeter  may 
be  used.  If  the  determination  is  to  be  made  with  a  colorimeter 
of  the  third  type  described  on  page  44,  make  the  solutions  to 
the  same  volume  in  the  following  manner.  Prepare  the  solutions 
in  two  large  test-tubes,  each  with  a  graduation  to  indicate  a 
volume  of  50  cc.  From  the  250-cc.  flask  containing  the  solution 
of  ore  transfer  50  cc.  to  one  of  the  tubes;  to  the  other,  add  a 
sufficient  quantity  of  ferric  sulphate  solution  to  contain  the  same 
amount  of  iron  that  is  contained  in  50  cc.  of  the  solution  of  ore. 
Add  to  this  5  cc.  of  the  standard  titanium  solution  (or  more  if 
necessary,  accurately  measured)  and  make  up  to  the  graduation 
with  dilute  sulphuric  acid  (3  :  100).  Then  add  to  each  tube  5  cc. 
of  solution  of  hydrogen  peroxide,  mix,  and  transfer  to  the  color- 
imeter for  comparison. 

Rare  Elements  in  Iron  Ore.  Methods  for  determining  other 
elements  in  ores  may  be  found  by  referring  to  the  index. 

ANALYSIS   OF   IRON   AND   STEEL 

Sampling.  Sampling  is  best  done,  as  explained  on  page  9, 
while  the  metal  is  still  molten.  The  samples  are  taken  with  an 
iron  hand-ladle  while  the  metal  is  being  poured.  If  the  metal 
is  poured  into  large  ladles  for  transfer  to  another  part  of  the 
plant,  one  sample  is  taken  from  each  ladle,  and  the  drillings  from 
these  are  mixed  for  the  final  sample.  In  the  case  of  cast-iron,  the 
molten  metal  is  poured  from  the  sampling  ladle,  either  upon  an 
iron  plate  or  into  a  mold.  If  the  sample  is  to  be  crushed  after 
cooling  it  is  best  to  let  it  cool  in  a  thin  layer.  If  it  is  to  be 
drilled,  the  mold  should  be  an  inch  or  so  in  depth.  A  very 
convenient  mold  (Fig.  61)  described  by  Camp  *  consists  of  two 
sections,  which  gives  a  casting  6  ins.  long  and  1J  ins.  thick,  to 
which  is  attached  at  one  end  a  section  J  in.  thick.  The  latter  is 

*  Met.  and  Chem.  Eng.,  10,  p.  668. 


104 


METALLURGICAL  ANALYSIS 


FIG.  61. — A  Sample  of  Cast-iron  and 
Mold  in  which  the  Sample  is  Cast. 


broken  off  and  crushed   for  analysis  and  the  large  section  is  used 

for  physical  tests.    . 

As  shown  by  Howe  *  and  others  t,  the  impurities  in  steel 

tend  to  segregate  on  cooling  in 
those  parts  which  freeze  last. 
Therefore,  to  obtain  a  represen- 
tative sample  of  the  metal  in 
solid  form,  it  is  necessary  to  drill 
well  into  the  metal;  and  to  be 
sure  that  the  material  comes 
within  the  specifications  axial 
drillings  should  be  taken,  and 
these  should  be  analyzed  as  a 
separate  sample. 
Steel  drillings  should  be  well  mixed,  and  since  the  fine  and  the 

coarse  differ  in  composition,  the  weight  taken  for  analysis  should 

consist  of  both  fine  and  coarse  in  the  same  ratio  that  exists 

between  them  in  the  sample  as   a   whole.     See  weighing  for 

analysis,  page  18. 

If  the  sample   of  cast-iron  is  crushed,  it  should  be  made  to 

pass  through  an  80-mesh  sieve,  and  all  that  will  not  pass  through 

such  a  sieve  should  be  rejected. 

DETECTION  OF  SEGREGATIONS  OF  SULPHUR 

Sulphur  occurs  in  steel  as  MnS,  but  if  there  is  not  enough 
manganese  present  to  combine  thus  with  all  the  sulphur,  the 
excess  of  sulphur  combines  with  iron  as  FeS.  Therefore,  to 
detect  segregations  of  sulphur  on  the  surface,  spread  a  piece  of 
white  silk  cloth  moistened  with  a  solution  of  lead  acetate  on  the 
surface  of  the  metal,  and  then  drop  dilute  hydrochloric  acid 
on  the  silk.  The  dilute  hydrochloric  acid  liberates  hydrogen 


*  Trans.  Amer.  Inst.  Min.  Eng.,  38,  104. 

f  Sauveur,  "  The  Metallography  of  Iron  and  Steel,"  6,  10. 


SILICON  IN  IRON  AND   STEEL  105 

sulphide  from  the  metallic  sulphide  and  this  precipitates  black 
lead  sulphide  on  the  silk  directly  over  the  segregations.  Photo- 
graphic printing  paper  moistened  with  dilute  sulphuric  acid  and 
pressed  against  the  surface  of  the  polished  metal  serves  this  pur- 
pose well. 

SILICON  IN  IRON  AND  STEEL  * 

Reagent.  Nitric  acid,  HNOs  (sp.gr.  1.2).  To  make  1  liter 
mix  391  cc.  HN03  (1.42)  with  646  cc.  H2O. 

Si  in  Steel.  Weigh  4.693  gms.,  transfer  it  to  a  beaker,  add  40 
cc.  of  dilute  nitric  acid,  and  warm  to  dissolve. 

FeSi+6HNOa=Fe(NO,),+H,SiOa+2H,0+N,Oa+NO. 

Low  carbon  steels  dissolve  very  readily.  If  the  action  becomes 
too  violent,  and  there  is  danger  of  loss,  place  the  beaker  in  a  dish  of 
cold  water. 

When  the  metal  is  dissolved,  evaporate  the  solution  to  dry  ness 
and  raise  the  temperature  until  ferric  nitrate  is  decomposed. 
Cool,  add  30  cc.  of  hydrochloric  acid  and  heat  until  the  ferric 
oxide  is  dissolved.  Evaporate  the  solution  to  dryness.  Redis- 
solve  in  30  cc.  of  hydrochloric  acid  and  dilute  to  150  cc.  Filter, 
wash  with  hot  dilute  hydrochloric  acid  and  cold  water  alter- 
nately until  the  precipitate  is  free  from  iron. 

If  washed  with  hot  water,  there  is  danger  of  precipitating  basic  salts  of 
iron  in  the  filter  in  the  absence  of  an  excess  of  acid.  (See  p.  52.) 

Burn  off  the  carbon  of  the  filter  paper  in  a  platinum  crucible 
with  a  Bunsen  burner  and  then  drive  off  the  last  traces  of  water 
with  the  highest  heat  of  the  blast  lamp.  Cool  in  a  desiccator 
and  weigh  the  silica.  The  weight  multiplied  by  10  gives  the 
percentage  of  silicon  in  the  steel. 

If  the  silica  weighed  is  not  pure,  it  may  be  treated  with  hydro- 
fluoric acid  and  sulphuric  acid,  according  to  the  method  given  on 
page  71,  and  the  impurity  weighed  and  deducted. 
*  Camp.  Met.  and  Chem.  Eng.,  10,  p.  669. 


106  METALLURGICAL  ANALYSIS 

SILICON  IN  STEEL 

BROWN'S  METHOD  * 

Reagents.    Silicon   mixture.     Dilute   300   cc.    HN03    (1.42) 
with  600  cc.  of  water  and  add  to  it  125  cc.  H2SO4  (1.84). 
Hydrochloric  acid,  HC1,  dilute,  (1  :  1). 

Si  in  Steel.  Weigh  4.693  gms.  of  steel  and  transfer  it  to 
casserole.  Add  60  cc.  of  the  silicon  mixture.  Warm  to  dis- 
solve the  steel,  and  evaporate  the  solution  until  the  sulphuric 
acid  fumes  freely. 

The  determination  should  be  covered  with  an  inverted  funnel  to  pre- 
vent loss  by  spattering. 

Cool,  add  10  cc.  of  dilute  hydrochloric  acid  and  50  cc.  of  hot 
water.  Warm  until  the  soluble  salts  are  in  solution.  Filter 
and  wash,  alternately,  with  hot  dilute  hydrochloric  acid  and  cold 
water  until  the  iron  salts  are  removed,  and  then  complete  the 
washing  with  hot  water.  Burn  the  filter  and  residue  in  a  plati- 
num crucible  and  proceed  according  to  the  method  described 
on  page  105. 

SILICON  IN  IRON 

DROWN'S  METHOD 

Weigh  0.4693  gm.  (twice  the  factor  weight,  0.9386,  may  be 
taken  if  the  iron  is  low  in  silicon),  transfer  it  to  a  porcelain 
casserole,  add  20  cc.  of  the  silicon  mixture,  and  proceed  accord- 
ing to  Drown's  method  for  Si  in  steel.  The  weight  of  SiC>2 
multiplied  by  100  gives  the  percentage  of  silicon  in  the  iron: 
or,  if  twice  the  factor  weight  was  used,  after  multiplying  by 
100,  divide  the  result  by  2. 

*  Trans.  Amer.  Inst.  Min.  Eng.,  7,  p.  346. 


SILICON  IN  IRON  107 

SILICON  IN  IRON 

FORD'S  METHOD 

Weigh  0.4693  gm.  of  the  finely  pulverized  sample  and  transfer 
it  to  a  platinum  dish  or  porcelain  casserole.  Add  20  cc.  of  con- 
centrated hydrochloric  acid,  cover  with  a  watch  glass,  and  boil 
rapidly  to  complete  dryness.  Without  cooling  (if  the  deter- 
mination is  in  platinum),  add  20  cc.  of  dilute  hydrochloric  acid 
(1:1).  Heat  a  few  minutes,  add  50  cc.  of  hot  water,  and  continue 
heating  to  dissolve  the  iron.  Filter,  and  proceed  according  to 
Brown's  method. 

This  method  is  not  so  accurate  as  Brown's  method,  but  it  is  rapid, 
and  the  rapidity  may  be  increased  by  filtering  with  suction,  using  a 
perforated  platinum  cone  to  support  the  filter  paper,  and  finally  by 
burning  the  precipitate  in  an  atmosphere  of  oxygen.  (See  Fig.  31.) 

SILICON  IN  FERRO-SILICON 

The  silicon  in  ferro-silicon  and  other  high  silicon  products 
may  be  determined  in  the  same  way  as  silicon  in  iron,  if  the  mate- 
rial is  soluble  in  acids.  If  very  high  in  silicon  the  powder  must 
be  fused  with  an  alkali  or  an  alkaline  salt  and  the  fusion  dis- 
solved and  treated  according  to  the  method  for  SiO2  in  ores, 
page  72.  Since  the  material  is  high  in  silicon,  only  a  small  por- 
tion is  necessary  for  the  sample. 

Si  in  Ferro-silicon.  Weigh  0.4693  gm.  Fuse  with  a  mixture 
of  20  gms.  of  sodium  carbonate  and  4  gms.  of  potassium  nitrate.* 

Blair  recommends  that  the  material  be  fused  with  sodium  per- 
oxide,! and  Preuss  prefers  10  gms.  of  KOH  in  a  nickel  crucible. t 

When  the  fusion  is  complete,  cool  it  and  dissolve  it  in  water 
and  hydrochloric  acid  and  evaporate  the  solution  to  dryness. 

*  Johnson,  "  Chem.  Anal,  of  Special  Steels,"  p.  120. 
t  Chem.  Anal,  of  Iron  and  Steel,  p.  224. 
j  Z.  Angew.  Chem.,  23,  p.  201. 


108  METALLURGICAL  ANALYSIS 

Dissolve  the  residue  in  hydrochloric  acid  and  water,  filter,  and 
evaporate  the  filtrate  to  dryness,  dissolve  this  residue  in  a  little 
hydrochloric  acid  and  water,  and  filter  a  second  time.  Burn 
the  precipitates  together  in  a  platinum  crucible  and  weigh. 
The  silicon  is  then  purified  with  hydrofluoric  acid  and  sul- 
phuric acid  in  the  usual  way.  If  the  precipitate  of  silica  is 
large,  a  second  treatment  with  the  acids  will  be  necessary  to 
remove  all  the  silica.  The  loss  in  weight  (SiCb)  multiplied  by 
100  gives  the  percentage  of  Si  sought. 

SULPHUR  IN  STEEL 

OXIDATION  WITH  NITRIC  ACID 

Reagents.    Dilute  hydrochloric  acid  (1  :  10). 

Sodium  carbonate,  Na2COs. 

Barium  chloride  solution.  Dissolve  10  gms.  BaCb  in  100  cc. 
of  water. 

S  in  Steel.  Weigh  4.579  gms.  of  steel  (one-third  the  factor 
multiplied  by  100),  transfer  it  to  a  500-cc.  beaker,  and  add  40 
cc.  of  strong  nitric  acid. 

3MnS+12HNO,=Mn,(S04)i+Mn(NOa)i+9NO+6H,0. 

Low-carbon  steels  dissolve  freely  in  strong  nitric  acid.  If  the 
action  is  too  violent,  place  the  beaker  in  cold  water.  High-carbon 
steels  dissolve  in  strong  nitric  acid  with  great  difficulty  and  strong 
hydrochloric  acid  should  be  added,  a  few  drops  at  a  time,  to  hasten 
the  solution.  If  too  much  hydrochloric  acid  is  added,  there  is  danger 
of  loss  of  sulphur  by  the  formation  of  H2S.  If  dilute  nitric  acid  were 
used,  the  sulphur  would  be  liberated,  but  not  oxidized  to  the  sulphate. 

In  dissolving  high  carbon  steels,  if  the  acid  is  reduced  by  evaporation 
to  a  small  volume  before  solution  takes  place,  more  acid  should  be  added. 

When  the  steel  is  in  solution  add  about  "0.5  gm.  of  sodium 
carbonate  and  evaporate  the  solution  to  dryness  in  an  air  bath. 

Silica  must  be  dehydrated  and  filtered  from  the  solution  and  the 
nitric  acid  replaced  by  hydrochloric,  before  precipitation  of  the  sulphur. 


SULPHUR  IN  STEEL  109 

Cooi  the  residue  and  add  30  cc.  of  strong  hydrochloric  acid. 
When  in  solution  add  about  0.5  gm.  of  sodium  carbonate  and 
evaporate  the  solution  to  dryness  in  an  air-bath. 

If  the  temperature  should  be  raised  high  enough  to  break  up  man- 
ganic or  ferric  sulphate,  the  sulphuric  acid  would  be  retained  as  sodium 
sulphate,  which  is  stable  at  a  high  temperature. 

Nitric  acid  must  be  removed,  since  it  interferes  with  the  precipita- 
tion of  barium  sulphate. 

Redissolve  the  residue  in  hydrochloric  acid  and  evaporate 
the  solution  until  ferric  chloride  begins  to  separate,  to  expel 
the  free  hydrochloric  acid.  Add  2  cc.  of  hydrochloric  acid. 

An  excess  of  hydrochloric  acid  is  necessary  for  the  formation  of  the- 
precipitate,  but  the  excess  should  be  small,  since  barium  sulphate  is. 
slightly  soluble  in  hydrochloric  acid. 

Dilute  the  solution  with  an  equal  volume  of  water.  Filter 
and  wash  with  cold  water. 

The  nitrate  and  washings  should  not  exceed  100  cc.,  since  the  pre- 
cipitation is  better  in  a  moderately  concentrated  solution;  if  too  dilute, 
the  iron  may  separate  and  be  carried  down  with  the  barium  sulphate. 

Heat  the  filtrate  to  boiling  and  add,  drop  by  drop,  10  cc.  of 
hot  barium  chloride  solution. 

Then  add  10  cc.  more  of  barium  chloride  solution,  boil  a  few 
minutes,  let  the  precipitate  settle  for  half  an  hour,  or  longer  if  con- 
venient, in  a  warm  place,  filter  and  wash  alternately  with  warm 
dilute  hydrochloric  acid  and  cold  water,  and  finally  wash  with 
water  until  the  washings  are  free  from  barium.  (See  p.  75.) 
Burn  the  filter  and  its  contents  in  a  weighed  platinum  crucible, 
cool,  and  weigh  the  BaSCU.  The  factor  for  sulphur  in  barium 
sulphate  is  0.13738.  If  the  weight  of  steel  specified  at  the 
beginning  of  this  method  was  used,  to  obtain  the  percentage  of 
sulphur,  multiply  the  weight  of  barium  sulphate  by  3, 


110  METALLURGICAL  ANALYSIS 

SULPHUR  IN  IRON 

AMERICAN  FOUNDRYMEN'S  ASSOCIATION  METHOD  * 

Outline.  The  iron  is  dissolved  in  concentrated  nitric  acid, 
potassium  nitrate  added  to  oxidize  the  sulphur,  the  solution 
evaporated  to  dryness  and  heated  to  drive  out  nitric  acid,  the 
potassium  retaining  the  sulphur  as  sulphate.  The  residue  is 
treated  with  sodium  carbonate  solution  to  dissolve  sulphates, 
filtered,  the  filtrate  acidified,  and  taken  to  dryness.  The 
residue  is  taken  up  with  dilute  hydrochloric  acid,  the  silica 
filtered  from  the  solution  and  the  sulphur  precipitated  from  the 
filtrate  with  barium  chloride. 

Reagents.     Potassium  nitrate,  KNOs. 

Solution  of  sodium  carbonate.  Dissolve  10  gms.  Na2COs  •  lOH^O 
in  1  liter  of  water. 

Barium  chloride  solution.  Dissolve  10  gms.  BaCl2  in  100  cc. 
of  water. 

S  in  Iron.  Weigh  3  gms.  of  drillings  for  the  sample  and  trans- 
fer it  to  a  platinum  dish.  Cover  the  dish  with  a  watch  glass 
and  dissolve  the  sample  slowly  in  concentrated  nitric  acid. 
When  the  iron  is  completely  dissolved  add  2  gms.  of  potassium 
nitrate.  (See  note  on  sodium  nitrate,  p.  73.)  Evaporate 
the  solution  to  dryness  and  ignite  the  residue  over  an  alcohol 
lamp  at  a  red  heat.  Cool,  add  50  cc.  of  the  1  per  cent  solu- 
tion of  sodium  carbonate.  Boil  a  few  minutes. 

The  sulphate  is  taken  into  solution  as  alkaline  sulphate  and  the 
iron  left  as  ferric  oxide. 

Filter,  wash  the  precipitate  with  hot  1  per  cent  solution  of 
sodium  carbonate,  acidify  the  filtrate  with  hydrochloric  acid, 
evaporate  the  solution  to  dryness,  and  dissolve  the  residue  in 
50  cc.  of  water  and  2  cc.  of  hydrochloric  acid.  Filter  and 
wash  the  Si02.  Dilute  the  filtrate  to  100  cc.,  heat  it  to  boiling, 

*  Chem.  Eng.,  4,  p.  213. 


SULPHUR  IN  IRON   OR  STEEL  111 

and  add  barium  chloride  solution  in  the  manner  described  in 
the  preceding  method.  Filter,  wash  the  precipitate  well  with 
hot  water,  ignite,  and  weigh.  Multiply  the  weight  of  BaSCU 
by  the  factor  for  S,  0.13738,  divide  the  result  by  3,  and  multiply 
by  100. 

SULPHUR  IN  IRON  OR  STEEL 

EVOLUTION  METHOD  * 

Outline.  The  steel  is  dissolved  in  hydrochloric  acid  in  a 
flask  and  the  H2$  formed  is  absorbed  in  an  alkaline  solution 
of  cadmium  chloride,  the  H2$  is  liberated  in  the  solution  with 
hydrochloric  acid  and  is  titrated  with  standard  iodine  solution. 

Reagents.  Standard  iodine  solution.  Place  3.958  gms.  of 
pure  iodine  in  a  liter  flask  with  about  6  gms.  of  potassium  iodide 
and  10  cc.  of  water.  Let  the  flask  stand  without  heating  until 
all  the  iodine  has  been  dissolved,  then  dilute  with  water  to 
the  graduation.  One  cubic  centimeter  of  this  solution  should 
be  equivalent  to  0.0005  gm.  of  sulphur.  If  5  gms.  of  material 
are  taken  for  analysis,  1  cc.  of  this  solution  will  then  be  equiv- 
alent to  0.01  per  cent  sulphur.  The  solution  should  be  stand- 
ardized against  a  steel  in  which  the  sulphur  has  been  previously 
determined,  and  either  corrected  to  the  above  value,  or  a  factor- 
weight  of  steel  taken  so  that  1  cc.  of  the  solution  will  be  equiv- 
alent to  0.01  per  cent  S.  (See  Factor  Weights  for  Standard 
Solutions,  p.  40.) 

Starch  solution.  Make  an  emulsion  of  about  1  gm.  of  starch 
in  4  cc.  of  cold  water.  Pour  this  slowly  into  about  200  cc.  of 
boiling  water  and  boil  five  minutes  after  the  starch  has  been 
added.  Cool  to  room  temperature  and  add  1  gm.  of  zinc  chloride 
dissolved  in  10  cc.  of  cold  water.  Mix  well  and  let  it  stand 
twenty-four  hours  or  more,  shaking  it  occasionally.  Decant  the 

*Camp,  Met.  and  Chem.  Eng.,  10,  p.  669.  Philips,  Stahl  u.  Eisen, 
16,  p.  633. 


112 


METALLURGICAL  ANALYSIS 


clear  solution  for  use.  The  zinc  chloride  is  added  as  a  pre- 
servative, since  it  prevents  the  growth  of  vegetable  molds. 

The  starch  solution  gives  a  much  more  delicate  end-point 
if  the  starch,  of  which  it  is  made,  has  been  soaked  twenty-four 
hours  in  very  dilute  hydrochloric  acid,  and  then  washed,  dried, 
and  heated  three  hours  in  an  oven  at  100°  C.* 

Cadmium  chloride  solution.  Dissolve  5  gm.  CdCU  in  375 
cc.  of  water  mixed  with  625  cc.  of  ammonia. 

Apparatus.  The  steel  is  dissolved  in  a  Florence  or  Erlen- 
meyer  flask,  fitted  with  a  2-hole  stopper,  through  which  pass  a 


FIG.  62. — Apparatus  for  Determination  of  Sulphur.     Evolution  Method. 

thistle  tube  or  separatory  funnel  and  a  delivery  tube.  The 
delivery  tube  above  the  flask  should  lead  upward  from  the  flask 
a  few  inches,  and  should  be  enlarged  so  that  the  condensation 
will  return  to  the  flask.  Beyond  the  enlargement  the  delivery 
tube  passes  down  through  a  2-hole  stopper  to  the  bottom  of  a 
small  Erlenmeyer  flask  or  a  large  test-tube,  containing  cadmium 
chloride  solution,  in 'which  the  H^S  is  absorbed.  From  the  other 
hole  in  the  stopper  of  the  absorbent  flask,  a  delivery  tube  of 
glass  or  fused  quartz  passes  horizontally  through  a  Bunsen 
flame,  and  then,  with  a  right-angle  bend,  passes  vertically 

*  Chem.  Abs.,  4,  2617. 


SULPHUR  IN  IRON  OR  STEEL  113 

downward   to   the   bottom   of  another   similar   absorbent   flask 
or  test-tube  containing  cadmium  chloride  solution.     (Fig.  62.) 
S  in  Steel.     Weigh  5  gms.  (or  a  factor  weight)  of  steel  p 
transfer   it    to    the    solution    flask    described    above.     Place    in 
each  of  the  small  absorbent  flasks  or  test-tubes  15  cc.  of  cad- 
mium  chloride   solution   diluted   to   60   cc.   with   water.     Heat 
the  quartz  tube  between  the  two  absorbent  flasks  to  redness. 

When  steel,  especially  high-carbon  steel,  is  dissolved  in  hydrochloric 
acid,  all  the  sulphur  is  not  liberated  in  the  form  of  H2S,  but  a  considerable 
part  is  combined  with  hydrocarbons,  one  of  which,  (CH3)S2,  has  been 
identified  by  Phillips.  These  mercaptans  are  not  very  volatile,  and  when 
they  pass  over  with  the  H^S  they  are  not  completely  absorbed  by  the 
cadmium  chloride  solution.  These  difficulties  may  in  a  measure  be 
obviated  by  dissolving  the  steel  in  strong  hydrochloric  acid,  by  boiling 
briskly  at  the  end  of  the  operation,  and  by  passing  the  unabsorbed 
gas  from  the  first  cadmium  chloride  flask  through  a  red-hot  tube 
before  it  enters  the  second  flask.  The  sulphur  in  the  unabsorbed  com- 
pounds is  changed  by  heat  into  H2S,  which  is  absorbed  in  the  second 
cadmium  chloride  flask. 

From  the  separatory  funnel  run  into  the  solution  flask  50  cc. 
of  hydrochloric  acid  and  close  the  tap  of  the  funnel.  Warm  the 
flask  so  that  the  steel  will  dissolve  briskly. 

MnS+2HCl  =  MnCl2+H2S/ 

Dilute  hydrochloric  acid  (1  :  1)  is  often  used  in  this  method,  but 
the  difficulties,  owing  to  the  formation  of  mercaptans,  as  mentioned 
above,  are  lessened  by  the  use  of  strong  acid. 

After  the  steel  is  dissolved  boil  the  solution  until  the  vapor 
has  carried  over  into  the  absorbent  all  the  sulphur  producfs 
that  are  volatile. 

H2S+CdCl2  =CdS+2HCl, 
HC1+NH4OH  =NH4C1+ H2O. 

Before  allowing  the  solution-flask  to  cool,  open  the  tap  of  the 
separatory  funnel  to  prevent  the  formation  of  a  partial  vacuum 


114 


METALLURGICAL  ANALYSIS 


in  the  flask,  which  would  draw  in  the  cadmium  chloride  solu- 
tion. Disconnect  the  two  absorbent  flasks  and  empty  them 
into  a  500-cc.  beaker,  being  careful  to  wash  all  of  the  cadmium 
sulphide  from  the  delivery  tubes  and  flasks  into  the  beaker. 
Dilute  the  solution  to  400  cc.  with  cold  water,  add  10  cc. 
of  starch  solution,  and  enough  hydrochloric  acid  to  dissolve 
the  cadmium  sulphide  and  to  render  the  solution  acid. 

CdS+2HCl  =  H2S+CdCl2, 

Stir  gently  to  mix  the  solution  well  and  titrate  at  once  with 
standard  iodine  solution  to  a  strong  blue  color. 

H2S+I2=2HI+S. 

The  solution  should  be  mixed  so  that  no  part  of  it  will  be  ammoniacal 
when  titration  begins.  To  prevent  the  escape  of  H2S  the  solution 
should  not  be  stirred  briskly.  There  should  be  sufficient  volume  to  hold 
the  H2S  in  solution;  it  should  be  cool  and 
the  titration  should  begin  promptly,  before 
there  is  time  for  H2S  to  escape.  The  end- 
point  is  the  familiar  blue  color  produced 
by  the  combination  of  starch  and  free 
iodine. 

When  accuracy  must  be  sacrificed 
for  the  sake  of  speed,  this  method  may 
be  simplified  by  dispensing  with  the 
quartz  tube  and  the  second  absorption 
flask.  For  rapid  work  the  apparatus 
usually  consists  of  an  Erlenmeyer  flask 

,    fitted  with  a  2-hole  stopper  which  carries 
JIG.  63. — Apparatus  for  Sul-       ,,  .  ,,       ,    ,       »        ,,        ..."        ,  .. 

phur.    Rapid  Method.       a  tmstle    tube   for    the    introduction    of 
acid  and  a  delivery  tube,  terminating  in 
a  large  test-tube  which  contains  the  absorbent.     (Fig.  63.) 


CARBON  IN  STEEL  115 

CARBON  IN  STEEL 

SOLUTION  AND  COMBUSTION 

Outline.  The  steel  is  dissolved  in  an  acid  solution  of  the 
double  chloride  of  copper  and  potassium,  which  leaves  all  the 
carbon  as  a  residue.  The  carbon  is  filtered  from  the  solution 
and  burnt  to  CO2  in  a  combustion  furnace.  The  CO2  is  absorbed 
in  a  solution  of  potassium  hydroxide  and  weighed. 

Reagents.  Solvents.  Solution  of  copper  and  potassium  chlor- 
ide. Dissolve  140  gms.  CuCl2-2KCl-2H20  in  400  cc.  of  water 
and  60  cc.  of  hydrochloric  acid  (sp.gr.  1.2). 

A  solution  of  copper  and  ammonium  chloride  may  be  used  as 
a  solvent,  but  the  potassium  salt  is  usually  freer  from  carbona- 
ceous impurities. 

If  steel  is  dissolved  in  the  ordinary  acids,  some  of  the  carbon 
escapes  in  gaseous  form.*  The  copper  and  potassium  chloride 
solution  dissolves  the  iron  and  leaves  the  carbon  in  solid  form. 

Absorbent  of  CO2-  Solution  of  potassium  hydroxide  (sp.gr. 
1.2).  Dissolve  300  gm.  of  KOH  in  1  liter  of  water.  Owing  to 
possible  impurities  in  the  solution,  which  will  absorb  oxygen  while 
the  combustion  is  going  on,  the  solution  should  have  oxygen 
passed  through  it  while  it  is  hot,  or  it  may  be  titrated  while  hot 
to  a  faint  green  with  potassium  permanganate  solution.  The 
potash  bulbs  should  be  filled  to  about  two-thirds  of  their  capacity 
with  this  solution.  The  bulbs  should  be  refilled  with  fresh 
solution  after  they  have  absorbed  about  0.5  gm.  of  CO2. 

After  a  bulb  is  filled,  dry  off  the  outside  and  the  inside  of 
the  entrance  tube.  The  inside  may  be  dried  with  a  small  roll  of 
filter  paper.  If  the  inside  is  not  dried,  a  deposit  of  potassium 
carbonate  may  choke  the  tube. 

Absorbents      of     Moisture.      Calcium    chloride;    dehydrated 

*  For  the  forms  of  carbon  in  steel,  see  Sauveur,  "  Metallography  of  Iron 
and  Steel,"  14,  8. 


116  METALLURGICAL  ANALYSIS 


Fused  calcium  chloride  should  not  be  used,  since  it  con- 
tains some  CaO,  which  would  absorb  CCb- 

Soda-lime,  a  mixture  of  sodium  hydroxide  and  lime,  is  a 
drying  agent,  and  is  also  a  better  absorbent  of  C02  than  potas- 
sium hydroxide  solution.  It  is  not  used  alone,  since  it  is  soon 
saturated,  but  follows  the  bulb  containing  potassium  hydroxide 
solution  to  take  out  the  last  traces  of  C02. 

These  drying  agents  should  be  in  granular  form  with  grains 
only  a  few  millimeters  in  diameter  and  free  from  dust.  All 
that  will  pass  through  a  20-mesh  sieve  should  be  discarded. 

Potassium  hydroxide  broken  up  quickly  and  placed  in  a  tube 
may  be  used  as  a  drying  agent.  It  also  absorbs  C02. 

Absorbents  of  Hydrochloric  Acid.  Anhydrous  copper  sul- 
phate. Saturate  small  pieces  of  pumice  with  a  strong  solution 
of  CuS04  and  heat  in  a  dish  to  drive  off  all  the  water.  This 
is  also  an  absorbent  of  water. 

A  saturated  solution  of  Ag2S04  in  sulphuric  acid  (sp.gr.  1.4). 

Oxidizing  Agents.  Copper  oxide.  Make  a  square  of  cop- 
per gauze  15  cm.  on  the  edge  into  a  roll  about  2  cm.  in  diameter 
and  enclose  this  in  a  sheet  of  asbestos  to  protect  the  silica  tube 
from  the  copper  oxide  formed.  Place  it  in  the  combustion 
tube  and  heat  it  in  a  current  of  oxygen  or  air-  until  the  copper 
is  converted  to  CuO.  If  a  silica  tube  is  heated  in  contact  with 
copper  oxide,  the  copper  oxide  combines  with  the  silica  and  the 
tube  is  destroyed.  Hot  copper  oxide  converts  CO  to  CO2. 

Platinized  asbestos  may  be  used  for  this  purpose  instead  of 
copper  oxide. 

Absorbents  of  Chlorine.  A  roll  of  silver  foil  is  placed  in  the 
cooler  part  of  the  combustion  tube  beyond  the  copper  oxide. 
The  silver  foil  should  be  taken  from  the  combustion  tube 
occasionally  and  heated  in  a  current  of  hydrogen  to  free  it  from 
chlorine. 

A  bulb  containing  the  following  mixture  may  be  used  for  this 
purpose  : 


CAKIiuN   IN    STEEL 


117 


0.2  gm.  pyrogallic  acid  ( 

3  gms.  neutral  oxalate  of  potassium  (K2C2O4+H2O). 

4  drops  concentrated  sulphuric  acid. 
Add  water  to  make  20  cc. 


Apparatus.  Combustion  may  be  carried  out  in  a  fused  silica 
combustion  tube  heated  in  either  an  ordinary  gas  combustion 
furnace  or  in  an  electric  furnace.  The  silica  tube  should 
have  an  inside  diameter  of  about  22  mm.  and  a  length 
of  50  to  60  cm.  Combustion  tubes  are  also  made  of 
platinum,  porcelain,  and  hard  glass. 

The  electric  furnace   (Fig.  64  C)   consists  essentially 


FIG.  64. — Apparatus  for  the  Determination  of  Carbon  in 
Steel. 

of  an  alundum  tube,  about  30  mm.  inside  diameter 
(just  large  enough  to  receive  the  silica  combustion 
tube)  wound  with  nichrome  or  other  resistance  wire 
and  imbedded  in  a  non-conducting  refractory  ma- 
terial (magnesia  and  asbestos).  The  oxygen  or  air,  before 
being  admitted  to  the  combustion  tube,  is  passed  first  through 
a  bulb  A,  containing  potassium  hydroxide  solution,  and  then 
through  the  U-tube  B,  the  first  limb  of  which  contains  soda  lime, 
and  the  second,  dried  calcium  chloride. 

The  rubber  stoppers  in  the  combustion  tube  must  be  protected 
from  the  heat.  The  ends  of  the  tube  are  kept  cool  by  strips  of 
asbestos  cloth,  which  dip  in  water,  and  asbestos  plugs  held  in 


118  METALLURGICAL  ANALYSIS 

platinum  gauze  are  placed  just  inside  the  stoppers  to  protect 
them  from  radiant  heat. 

In  the  combustion  tube,  a  little  beyond  its  middle  point, 
toward  the  exit  end,  is  placed  the  roll  of  copper  oxide  enclosed 
in  a  sheet  of  asbestos,  and  beyond  that,  in  the  cooler  part  of 
the  tube,  a  roll  of  silver  foil  to  absorb  chlorine.  If  silver 
is  not  used,  the  chlorine  may  be  absorbed  by  passing  the  gases, 
after  they  leave  the  combustion  tube,  through  a  bulb  contain- 
ing potassium  oxalate  solution  (see  Reagents).  The  gases 
then  pass  through  the  U-tube  E,  which  contains  in  the  first 
limb  dehydrated  copper  sulphate,  and  in  the  second,  dry  cal- 
cium chloride.  From  this  tube  the  gas  passes  into  the  weighed 
potash  bulb  F,  and  from  that  to  the  tube  G,  which  is  also 
weighed,  and  which  contains  in  the  first  half  soda-lime,  and 
in  the  second,  dry  calcium  chloride.  A  larger  calcium  chloride 
tube  H  follows,  which  serves  as  a  protection  to  G  from  moisture, 
in  case  air  should  be  drawn  in  from  that  end  of  the  train. 

When  the  bulb  F  and  the  tube  G  are  detached  from  the  train 
to  be  weighed,  they  should  be  closed  with  stoppers  made  of  small 
pieces  of  rubber  tubing  closed  at  one  end  with  a  bit  of  glass  rod, 
if  they  are  not  provided  with  glass  stopcocks. 

If  air  is  used  for  combustion,  it  may  be  driven  through  the 
train  by  aspirator  bottles  attached  to  the  entrance  end  of  the 
train,  or  it  may  be  drawn  through  by  attaching  an  aspirator 
bottle  to  the  exit  end.  If  oxygen  is  used,  the  flow  is  regulated 
by  means  of  the  valve  on  the  oxygen  tank.  It  is  difficult  to 
regulate  the  flow  of  oxygen  through  the  combustion  train  from 
a  tank  at  high  pressure;  it  is  therefore  advisable  to  fill  tanks  at 
low  pressure  from  a  high-pressure  tank  for  use  in  combustion. 

Rubber  absorbs  appreciable  amounts  of  CCb;  therefore  the 
glass  apparatus  in  the  combustion  train,  connected  by  rubber 
tubing,  should  be  made  to  touch  inside  the  rubber  tubing  and 
thus  protect  the  rubber  from  contact  with  the  gas. 

When  the  boat  is  placed  in  the  combustion  tube,  the  train  is 


CARBON  IN  STEEL  119 

tested  for  leaks  by  closing  the  entrance  end  of  the  train  and 
slowly  exhausting  the  air  from  the  exit  end  by  suction.  When 
the  suction  is  removed,  the  atmospheric  pressure  will  cause  the 
caustic  solution  in  the  weighed  bulb  to  rise  in  the  side  next  the 
combustion  tube.  If  there  is  a  leak,  the  solution  will  gradually 
fall  back  to  the  original  level. 

When  the  train  is  made  perfectly  tight,  the  air  or  oxygen  is 
passed  through  at  the  rate  of  two  bubbles  per  second  and  the 
furnace  is  gradually  heated  to  a  bright  red  heat.  After  burning 
out  the  furnace  fifteen  minutes,  detach  the  potash  bulb  and  its 
tube,  cool  them  in  the  balance  case  fifteen  minutes,  and  weigh. 
Connect  them  to  the  train  again,  pass  the  oxygen,  and  burn 
fifteen  minutes,  cool  and  weigh  again.  This  is  repeated  until 
the  weight  is  constant. 

In  weighing  the  bulb  and  tube,  they  should  always  be  coun- 
terpoised by  a  similar  bulb  and  tube  so  that  the  error  due  to 
condensation  of  moisture  on  the  apparatus  may  be  avoided. 
Apparatus  should  not  be  weighed  after  it  has  been  rubbed  or 
wiped  off  with  a  cloth  until  it  has  stood  at  least  thirty  minutes 
for  the  dissipation  of  static  charges  of  electricity.  Richards 
and  Shipley  *  found  that  a  small  quartz  flask  which  was  2  mgms. 
too  light  from  this  cause  was  immediately  restored  to  its  nor- 
mal weight  by  bringing  into  the  balance  case  a  very  small  tube 
of  impure  radium  chloride. 

If  a  gas  furnace  is  used,  the  burners  next  the  ends  should  be 
lighted  first  and  after  an  interval  of  two  minutes  the  burners 
next  to  these  are  turned  on  and  so  on  until  the  last  to  be  lighted 
are  those  directly  under  the  platinum  boat. 

C  in  Steel.  Weigh  3  gms.  (or  ten  times  the  factor  weight, 
2.727  gms.)  of  steel,  transfer  it  to  a  500-cc.  beaker,  and  add  200 
cc.  of  copper  and  potassium  chloride  solution. 

When   ferro-alloys   and    chrome   tungsten   steels   are   dissolved    in 
copper  potassium  solution,  not  all  the  carbon  is  left  in  the  residue; 
*  Jour.  Am.  Chem.  Soc.  36  (1914)  4. 


120  METALLURGICAL  ANALYSIS 

therefore  a  direct  combustion  method  (see  p.  121)  should  be  adopted 
for  carbon  in  these  materials. 

If  a  little  fibrous  asbestos  is  added,  the  finely  divided  carbon  adheres 
to  it,  greatly  facilitating  filtering  and  washing. 

Keep  the  temperature  of  the  solution  below  40°  C.,  and 
stir  with  the  mechanical  stirrer  (see  Fig.  60)  until  the  steel  is 
dissolved. 

Fe+CuCl2=FeCl2+Cu, 
Cu+CuCl2=2CuCl. 

The  copper  is  first  precipitated  on  the  steel  and  is  then  slowly  dis- 
solved by  the  solution  of  cupric  chloride. 

When  the  steel  is  dissolved,  filter  the  solution  through  as- 
bestos in  a  small  Gooch  crucible  about  15  mm.  in  diameter  or 
in  a  perforated  platinum  boat. 

The  manner  of  attaching  the  Gooch  crucible  to  the  carbon  filter 
is  shown  in  Fig.  29,  page  25.  The  perforated  platinum  boat  is  most 
conveniently  attached  to  the  filter  flask  by  means  of  a  specially  made 
holder  of  soft  rubber  which  is  provided  with  a  trough-like  opening  in 
the  top  into  which  the  boat  is  pressed  to  make  the  connection  air-tight. 

The  asbestos  should  have  been  previously  burnt  to  free  it  from 
carbonaceous  matter. 

Wash  the  carbon  with  a  little  dilute  hydrochloric  acid  (1:1) 
and  then  with  water  until  it  is  free  from  acid. 

Filtering  and  washing  should  be  done  carefully  by  pouring  the  solu- 
tion down  a  glass  rod  into  the  boat.  A  jet  of  water  from  a  wash  bottle 
may  throw  particles  of  carbon  from  the  boat. 

Dry  the  Gooch  crucible  or  boat  and  its  contents  in  an  air-bath 
at  a  temperature  not  above  105°  C.  While  the  carbon  is  dry- 
ing, prepare  the  combustion  furnace  by  passing  oxygen  through 
the  hot  tube  until  the  combined  weight  of  the  bulb  F  and  the 
tube  G  is  constant.  Attach  the  weighed  bulb  and  tube  to  the 
train,  place  the  crucible  or  boat  containing  the  carbon  in  the 
combustion  tube  near  the  copper  oxide  and  burn  the  carbon 


TOTAL  CARBON  IN  IRON  OR  STEEL  121 

in  a  current  of  oxygen  or  air  at  the  rate  of  two  bubbles  per 
second  until  all  the  carbon  has  been  converted  to  C02  and 
carried  over  into  the  absorption  bulb.  The  operation  should 
be  complete  within  about  thirty  minutes. 

After  the  combustion  is  complete,  remove  the  absorption 
bulb  and  drying-tube  and  close  the  ends  with  the  stoppers 
described  on  page  118. 

The  absorbents  in  the  weighed  bulb  and  tube  should  always  be 
protected  from  moisture  and  C02  in  the  air  by  these  stoppers  when 
the  bulb  is  not  attached  to  the  combustion  train,  and  the  stoppers  should 
always  be  weighed  with  the  bulb.  The  train  itself  should  be  closed 
with  stoppers  similar  to  those  used  on  the  bulb,  when  the  bulb  is  removed 
for  weighing. 

There  should  always  be  the  same  amount  of  air  (or  oxygen,  if  that 
is  used  for  combustion)  in  the  bulb  when  it  is  weighed.  If  air  is  used 
for  combustion,  the  bulb  may  be  closed  by  capillary  stoppers  to  main- 
tain atmospheric  pressure  in  the  bulb;  when  oxygen  is  used,  if  the  bulb 
is  always  closed  when  it  is  about  the  same  temperature,  the  quantity 
of  oxygen  weighed  will  be  the  same. 

Let  the  bulb  and  tube  stand  in  the  balance  case  fifteen 
minutes  before  weighing. 

The  increase  in  weight  represents  the  CCb.  The  factor  for 
C  in  CO2  is  0.2727  or  A.  If  the  factor  weight  was  used, 
multiply  the  weight  of  CO2  by  10. 

TOTAL  CARBON  IN  IRON  OR  STEEL 

DIRECT  COMBUSTION 

Outline.  The  steel  is  burnt  directly  in  oxygen,  the  CO2 
formed  by  the  oxidation  of  the  carbon  in  the  steel  is  absorbed 
in  a  solution  of  potassium  hydroxide  and  weighed.  By  this 
method  the  carbon  from  carbonaceous  gases  in  the  steel  would 
also  be  included  in  the  determination. 

Reagents.  Alundum.  Ignited  alundum  is  placed  in  a 
platinum,  nickel,  alundum,  porcelain,  or  clay  boat  about  7  cm. 


122 


METALLURGICAL  ANALYSIS 


long.     A  depression  is  made  in  the  alundum    about  3  cm.  in 
length,  in  which  the  sample  is  placed  to  be  burnt  (Fig.  65). 


FIG.  65. — Boat  with  Steel  Ready  for  Combustion  and  Semi-cylindrical  Cover 
for  the  Protection  of  the  Silica  Tube  from  Iron  Oxide. 


FIG.  66. — Apparatus  for  the  Direct  Combustion  of  Steel  for  Carbon. 

Oxygen.  The  flow  of  oxygen  is  much  more  easily  regulated 
if  low-pressure  cylinders  are  filled  for  use  from  the  high-pressure 
tank. 


TOTAL  CARBON  IN  IRON  OR  STEEL        123 


Red  lead  oxide,  PbaCU.  Pig  iron  and  ferro-alloys  burn  more 
completely  at  the  usual  temperature  of  the  furnace  if  mixed  with 
a  little  red  lead  oxide. 

Potassium  hydroxide  solution.  Dissolve  300  gms.  of  KOH 
in  1  liter  of  water. 

Granulated  zinc  for  the  absorption  of  sulphuric  acid. 

Calcium  chloride,  CaCl2  dehydrated. 

Apparatus.  The  combustion  furnace  (Fig.  66)  is  similar  to 
that  described  on  page  117,  but  in  the  direct  combustion  of  steel 
the  temperature  of  the  furnace  should  be  maintained  at  about 
1000°  C.  It  should  not  fall  below  960°  or  rise  above  1050°  C. 
The  furnace  should,  therefore,  be  provided  with  a  pyrometer, 
or  the  resistance  in  the  rheostat  may  be  standardized  once  for 
all  so  that  the  temperature  may  be  known  approximately  by  the 
amount  of  resistance  in  the  circuit.  When  the  resistance  is 
standardized,  the  hot  junction  of  the  pyrometer  should  be  placed 
in  the  combustion  tube  at  the  point  where  the  carbon  is  to  be 
burnt. 

It  should  be  kept  in  mind  that  this  latter  method  of  controlling 
the  temperature  is  only  approximate  and  may  vary  as  much  as  40° 
to  50°  owing  to  changes  in  room  temperature,  air  currents,  and  vari- 
ation in  the  electric  current. 

Before  the  oxygen  enters  the  combustion  tube,  it  is  passed 
through  potassium  hydroxide  solution,  sulphuric  acid,  soda- 
lime,  and  calcium  chloride.  After  leaving  the  combustion  tube, 
the  gases  pass  through  a  column  of  granulated  zinc,  which 
removes  sulphuric  acid,  derived  from  the  sulphur  in  the  steel, 
and  through  calcium  chloride,  which  dries  them  before  they  enter 
the  weighed  bulb  and  tube.  A  roll  of  copper  oxide  enclosed  in 
sheet  asbestos  is  placed  in  the  combustion  tube  to  oxidize  CO 
to  C02,  or,  for  this  purpose,  plantinized  asbestos  may  be  sub- 
stituted. (See  p.  118.)  The  platinized  asbestos  occupies  12 
to  15  cms.  of  the  combustion  tube  immediately  following  the 
position  of  the  boat  and  is  held  in  place  with  thin  plugs  of  platinum 


124 


METALLURGICAL  ANALYSIS 


FIG.  67.— Glass-stoppered  Bulb 
and  Tube. 


gauze.     The  stoppers  in  the  combustion  tube  must  be  protected 
from  heat  in  the  way  described  on  page  117.     Before  determina- 
tions begin,  oxygen  should  be   passed  through  the  hot  combus- 
tion tube   at  intervals  and  the  ab- 
sorption bulb  and  tube  brought  to  a 
constant  weight.     (See  p.  119.) 

The  absorption  bulb  should  be 
provided  with  glass  stop-cocks,  and 
it  should  be  filled  with  oxygen  when 
weighed.  (Fig.  67.)  In  weighing, 
the  bulb  and  tube  should  be  counter- 
balanced with  a  similar  apparatus. 

C  in  Steel.  Weigh  0.2727  gm.  or  twice  the  factor,  0.5454 
gm.,  and  transfer  to  the  boat  described  above.  The  steel  drillings 
should  lie  in  a  continuous  mass  so  that  when  combustion  begins 
it  will  be  propagated  throughout.  Turn  a  semi-cylindrical  cover 
of  alundum  or  clay  over  the  drillings  to  protect  the  silica  tube 
from  the  iron  oxide  which  is  thrown  from  the  boat  during  com- 
bustion. Push  the  boat  thus  covered  into  place  in  the  combus- 
tion tube,  which  has  been  heated  to  1000°  C.  Close  the  com- 
bustion tube  and  pass  the  oxygen  through  at  a  uniform  rate  of 
about  four  bubbles  per  second  until  the  steel  begins  to  burn, 
when  the  rate  is  increased  until  the  rate  of  flow  in  the  forward 
bulb  is  equal  to  that  in  the  first  absorption  bulb.  The  com- 
bustion should  be  finished  in  about  ten  minutes.  The  gas  is 
cut  off  and  the  absorption  bulb  with  its  calcium  chloride  tube  is 
detached  from  the  train,  cooled  and  weighed. 


CARBON  IN  IRON  AND  STEEL 

WEIGHING  AS  BARIUM  CARBONATE  AFTER  DIRECT  COMBUSTION 

Outline.  The  steel  is  burnt  in  oxygen  in  a  combustion 
furnace,  the  carbon  of  the  steel  is  converted  to  CO2  which  is 
purified  and  absorbed  in  a  solution  of  barium  hydroxide.  The 


CARBON  IN  IRON  AND  STEEL  125 

precipitated  barium  carbonate  is  filtered  from  the  solution,  burnt, 
and  weighed. 

Reagents.  Barium  hydroxide  solution.  Dissolve  20  gms. 
of  Ba(OH)2+8H20  in  1  liter  of  freshly  boiled  hot  water.  Cover, 
and  when  cool  filter  as  rapidly  as  possible  into  a  receiver  which 
is  protected  from  the  CO2  of  the  atmosphere.  The  solution 
should  be  withdrawn  from  the  container,  for  use  through  a  tap 
or  siphon,  and  the  air  which  replaces  it  should  be  admitted  through 
a  tube  containing  soda-lime 
or  through  a  bulb  containing 
caustic  potash  solution. 

Apparatus.      Set    up    the 


combustion    furnace    in    the 

manner     described      in      the         FlG  68._Bulb  Tube  for  Barium 

method    above,    except    that  Hydroxide  Solution. 

part  of  the  train  following  the 

column  of  granulated  zinc  is  replaced  by  the  bulb  tube  (Fig.  68) 

which  should  contain  30  cc.  of  barium  hydroxide  solution. 

C  in  Iron  and  Steel.  Weigh  1  gm.  of  the  metal,  or  ten  times 
the  factor,  0.608  gm.,  and  proceed  in  the  manner  described 
in  the  preceding  method  until  combustion  is  complete. 

Ba(OH)2+C02  =BaC03+H20. 

Carefully  wash  the  barium  hydroxide  solution  with  its  pre- 
cipitate of  barium  carbonate  from  the  bulb  tube.  Filter  and 
wash  the  precipitate  several  times  with  freshly  boiled  water  as 
quickly  as  possible  to  prevent  absorption  of  C02  from  the 
atmosphere. 

Burn  the  filter  with  its  contents  in  a  platinum  crucible  at 
a  red  heat  with  a  Bunsen  burner,  cool  in  a  desiccator,  and 
weigh.  The  factor  for  carbon  in  BaCO3  is  0.0608.  If  the  factor 
weight,  0.608  gm.,  was  used,  multiply  the  weight  of  barium 
carbonate  by  10. 


126  METALLURGICAL  ANALYSIS 

CARBON  IN  IRON  AND  STEEL 

TlTRATION    OF   THE   EXCESS    OF   BARIUM    HYDROXIDE 

Outline.  The  steel  is  burnt  in  a  combustion  furnace  with 
oxygen.  The  C02  formed  by  the  oxidization  of  the  carbon  in 
the  steel  is  purified  and  passed  into  a  definite  volume  of  a  standard 
solution  of  Ba(OH)2.  The  excess  of  Ba(OH)2  is  measured  by 
titrating  with  standard  acid  and  the  weight  of  carbon  is  calculated. 

Reagents.  Standard  hydrochloric  acid.  Dilute  8  cc.  of 
HC1  (sp.gr.  1.2)  to  1  liter  with  freshly  boiled  water. 

Standard  barium  hydroxide  solution  prepared  in  the  manner 
described  on  page  125,  and  standardized  according  to  the  method 
given  below. 

Phenolphthalein  solution.  One  gram  of  phenolphthalein  dis- 
solved in  1  liter  of  ethyl  alcohol  (p.  84). 

To  determine  the  relative  values  of  the  acid  and  alkali  solu- 
tions, titrate  a  definite  volume  of  the  barium  hydroxide  solu- 
tion with  the  dilute  hydrochloric  acid,  after  adding  a  few  drops 
of  phenolphthalein  solution. 

To  determine  the  value  of  the  sodium  hydroxide  solution 
in  carbon,  weigh  a  steel  in  which  the  carbon  has  already  been 
determined  and  treat  it  exactly  as  described  in  this  method. 

Divide  the  weight  of  carbon  in  the  steel  by  the  number  of 
cubic  centimeters  of  barium  hydroxide  solution  required  to 
combine  with  it  to  form  BaCOs. 

C  in  Iron  or  Steel.  Weigh  the  iron  or  steel  and  proceed 
according  to  the  last  method  (see  p.  125),  with  the  following 
modification.  Measure  into  the  bulb-tube  with  the  pipette  30 
cc.  of  standard  barium  hydroxide  solution.  Burn  the  sample, 
passing  the  oxygen  in  the  usual  way  (p.  124).  After  the  com- 
bustion is  complete,  empty  the  barium  hydroxide  solution  with 
the  precipitate  of  barium  carbonate  into  a  half-liter  Erlenmeyer 
flask  and  wash  out  the  tube  well  with  freshly-boiled  water. 
Add  3  drops  of  phenolphthalein  solution  and  titrate  the  excess 


COMBINED  CARBON  IN   STEEL 


127 


of  barium  hydroxide  with  standard  hydrochloric  acid.  The 
value  of  1  cc.  of  the  barium  hydroxide  solution  in  carbon  is 
then  multiplied  by  the  number  of  cubic  centimeters  of  the  solu- 
tion from  which  the  barium  had  been  precipitated  by  the 


COMBINED  CARBON  IN  STEEL 

COLOR  METHOD 

Outline.  The  steel  is  dissolved  in  a  definite  volume  of 
dilute  nitric  acid.  The  intensity  of  the  brown 
color  of  the  solution  depends  upon  the  amount 
of  carbon  present.  This  solution  is  compared 
in  a  colorimeter  with  a  solution  of  a  standard 
steel  prepared  in  the  same  way. 

Reagent.     Dilute  nitric  acid  (1  :  3). 

C  in  Steel.  Weigh  0.5  gm.  of  steel  (0.2  gin. 
if  the  steel  is  high  in  carbon)  and  transfer  it  to 
a  large  test-tube.  Add  10  cc.  of  dilute  nitric 
acid  (1  :  3)  measured  with  a  pipette  (Fig.  69). 
At  the  same  time,  weigh  and  treat  in  the  same 
manner  a  standard  steel  in  which  the  carbon 
has  been  determined  by  combustion.  Place 
both  test-tubes  in  a  water  bath  (Figs.  70  and 
71)  and  heat  until  the  steel  is  dissolved.  When 
in  solution,  remove  the  test-tubes  and  place  them  in  cold  water. 
Dilute  the  solutions  to  the  same  volume  (50  cc.)  and  transfer 
to  a  colorimeter  and  read  the  percentage  of  carbon  directly 
(see  p.  44) ;  or  transfer  the  two  solutions  to  Eggertz  tubes  and 
dilute  until  the  two  agree  in  color. 

Carbon  in  steel  in  the  form  known  as  hardening  carbon  does  not 
give  any  color  to  the  nitric  acid  solution.  On  the  other  hand,  the 
solution  is  colored  by  copper,  cobalt,  and  chromium.  For  these  rea- 
sons the  standard  and  the  unknown  steel  should  have  as  nearly  the  same 
composition  as  possible,  and  should  have  received  the  same  treatment. 


FIG.  69.— Auto- 
matic Filling 
Pipette. 


128 


METALLURGICAL  ANALYSIS 


They  should  be  annealed  before  sampling  to  convert  the  carbon  in 
each  to  the  same  form. 

The  standard  should  be  near  the  unknown  in  its  carbon  content. 

The  colors  are  matched  best  if  the  light  comes  directly  from  the  sky 
or  clouds,  and  it  should  be  diffused  by  a  ground  glass. 

The  color  fades  on  exposure  to  light;  therefore  the  solution  should 
be  kept  in  the  dark  until  ready  for  comparison. 

If  there  is  much  difference  between  the  standard  and  the  unknown 
steel  in  carbon  content,  in  using  Eggertz  tubes,  there  is  a  tendency  to 
read  the  unknown  too  close  to  the  standard.  If  the  difference  is  as 
much  as  one-sixth  of  the  standard,  some  chemists  make  a  correction  of 
1  point  for  every  time  that  one-sixth  of  the  standard  is  contained  in 


FIG.  70.— Rack  Made  of  Copper  for  Hold- 
ing Test  Tubes  in  the  Water  Bath. 


FIG.  71.— Water 
Bath. 


the  difference  between  the  two;  for  example,  if  the  standard  is  0.48 
carbon  and  the  unknown  reads  0.56,  the  difference  is  8  points,  and  one- 
sixth  of  the  standard,  that  is,  8,  is  contained  in  this  difference  one  time. 
Therefore  add  1  to  the  reading  of  the  unknown  making  it  0.57  as  the 
correct  percentage.  If  the  standard  were  higher  than  the  unknown,  the 
correction  would  be  subtracted  from  the  reading  of  the  unknown. 

A  correction  is  also  sometimes  made  if  the  standard  and  the 
unknown  differ  widely  in  manganese.  Manganese  causes  the  carbon 
color  to  be  lighter,  and  if  the  unknown  steel  contains,  for  example, 
10  points  more  of  manganese  than  the  standard,  1  point  is  added  to 
the  reading  for  carbon  to  give  the  correct  percentage;  if,  on  the  other 
hand,  the  unknown  were  10  points  lower  in  manganese,  1  point  would 
be  subtracted  from  its  carbon  reading. 


GRAPHITIC  CARBON   IN  IRON  129 

GRAPHITIC  CARBON  IN  IRON 

Outline.  The  iron  is  dissolved  in  dilute  acid,  the  graphitic 
carbon  filtered  from  the  solution,  dried,  and  weighed,  or  it  may 
be  burnt  in  a  combustion  furnace,  the  resulting  C02  collected 
and  weighed. 

Reagents.     Dilute  nitric  add  (1  :  3).  ' 

Hydrofluoric  acid,  HF. 

Hydrochloric  acid,  dilute  (1  :  3). 

C,  graphitic,  in  Iron.  Weigh  0.608  gm.  of  the  sample  and 
transfer  it  to  a  small  beaker  or  Erlenmeyer  flask.  Add  40  cc. 
of  dilute  nitric  acid.  Heat  gently  to  dissolve  the  iron.  Add 
a  few  drops  of  hydrofluoric  acid  to  dissolve  silica,  and  boil  a 
few  minutes.  Filter  the  carbon  on  asbestos  in  a  small  Gooch 
crucible  or  in  a  perforated  platinum  boat.  Wash  with  hot 
dilute  hydrochloric  acid  and  water  alternately,  and  finally  wash 
with  hot  water  to  remove  the  acid.  Dry  the  carbon  in  the 
boat  at  110°  C.,  burn  in  a  combustion  furnace,  and  proceed 
according  to  the  method  for  carbon  !n  steel.  (See  p.  121.) 

The  graphite  may  be  filtered  on  asbestos  in  a  Gooch  crucible, 
washed,  and  dried  at  110°  C.  to  a  constant  weight.  After  weigh- 
ing, the  graphite  is  burned,  in  the  air  or  in  oxygen,  and  the 
crucible  and  residue  weighed.  The  loss  in  weight  represents 
the  graphite. 

PHOSPHORUS  IN  IRON  AND  STEEL 

Outline.  The  steel  is  dissolved  in  dilute  nitric  acid,  the 
solution  evaporated  to  dryness,  the  silica  dehydrated,  and  the 
phosphorus  oxidized  to  phosphate.  The  residue  is  taken  up 
with  hydrochloric  acid,  the  free  acid  expelled  by  evaporation, 
nitric  acid  added,  and  the  solution  evaporated  to  displace  all 
the  hydrochloric  acid.  The  solution  is  diluted,  the  silica  filtered 
from  it,  and  ammonia  and  nitric  acid  added  to  the  filtrate. 


130  METALLURGICAL  ANALYSIS 

The  phosphorus  is  then  precipitated  with  ammonium  molybdate, 
filtered,  and  weighed;  or  it  may  be  measured  by  titration. 

Reagents  and  Notes.     See  phosphorus  in  iron  ore,  page  76. 

P  in  Steel.  Weigh  1,63  gm.  (if  the  material  is  low  in  phos- 
phorus 4.89  gm. — 300  times  the  factor — may  be  used).  Trans- 
fer it  to  a  porcelain  casserole  or  dish  and  add  from  25  to  60  cc. 
of  dilute  nitric  acid  (l':.l).  Warm  cautiously  to  dissolve  the 
iron  and  evaporate  the  solution  rapidly  to  dryness.  Gradually 
increase  the  heat  until  the  ferric  nitrate  is  broken  up  and  the 
acid  is  all  expelled.  Cool  and  add  30  cc.  of  strong  hydrochloric 
acid,  heat  to  dissolve  the  iron  oxide,  and  evaporate  the  solution 
until  chlorides  begin  to  separate.  Add  10  cc.  of  strong  nitric 
acid  and  evaporate  the  solution  to  a  syrupy  consistency.  Dilute 
with  cold  water  to  about  60  cc.  Stir  and  filter  into  a  half-liter 
Erlenmeyer  flask.  Wash  alternately  with  2  per  cent  solution 
of  nitric  acid  and  hot  water  until  the  residue  is  free  from  iron. 

If  the  iron  contains  an  appreciable  amount  of  titanium,  ignite  the 
filter  and  residue  in  a  platinum  crucible.  Cool  and  treat  the  residue 
with  hydrofluoric  and  sulphuric  acids  to  remove  the  silica.  Evaporate 
the  solution  to  dryness,  add  a  little  sodium  carbonate,  and  fuse.  Treat 
the  fusion  with  hot  water  and  after  disintegration  filter  the  insoluble 
sodium  titanate  from  the  solution  and  add  the  filtrate  containing  the 
phosphate  to  the  main  solution. 

To  the  filtrate  containing  the  phosphorus  add  25  c.  of 
strong  ammonia. 

This  filtrate  should  be  clear  and  should  have  a  volume  of  about  150  cc. 

Shake  the  solution  vigorously,  add  nitric  acid,  and  proceed 
according  to  the  method  for  phosphorus  in  ores.  (See  p.  77.) 

Instead  of  weighing  the  yellow  precipitate  it  may  be  dissolved, 
the  phosphorus  precipitated  with  magnesia  mixture,  and  weighed 
as  magnesium  pyrophosphate  as  described  on  page  79;  or  the 
phosphorus  in  the  yellow  precipitate  may  be  measured  by  Emmer- 
ton's  volumetric  method  (p.  80),  or  by  Pemberton's  alkalimetric 
method  (p.  83). 


PHOSPHORUS  IN  IRON  OR  STEEL  131 

PHOSPHORUS  IN  IRON  OR  STEEL 
RAPID  METHOD 

Outline.  The  iron  is  dissolved  in  dilute  nitric  acid,  the 
carbon  oxidized  with  ammonium  persulphate,  the  solution 
filtered  from  the  residue,  the  phosphorus  in  the  filtrate  oxidized 
to  phosphate  with  potassium  permanganate,  the  resulting  man- 
ganese dioxide  reduced  and  dissolved  and  the  phosphorus  pre- 
cipitated with  ammonium  molybdate,  filtered,  and  measured  by 
titration  with  standard  sodium  hydroxide  solution. 

Reagents.    Ammonium  persulphate,  (NH4) 28203. 

Dilute  nitric  acid  (1  :  3). 

Wash  solution  of  nitric  acid  (1  :  48). 

Potassium  permanganate  solution.  Dissolve  25  gms.  KMnO4 
in  water  and  dilute  to  1  liter. 

Ammonium  molybdate  solution.     (See  p.  76.) 

Reducing  Agents.  Ammonium  bisulphite  solution.  Dissolve 
5  gms.  NH4HSO3  in  100  cc.  of  water. 

Ferrous  sulphate  solution.  Dissolve  5  gms.  FeS04+7H20 
in  100  cc.  of  water. 

Sugar  Solution.     A  saturated  solution  of  Ci2H22Ou  in  water. 

P  in  Iron  or  Steel.  Place  1.63  gms.  (or  other  factor  weight) 
of  the  iron  in  a  half-liter  Erlenmeyer  flask.  Add  40  cc.  of  dilute 
nitric  acid  (1  :  3)  and  heat  until  the  iron  is  dissolved.  When 
in  solution  wash  down  the  sides  of  the  flask,  add  1  gm.  of 
ammonium  persulphate,  and  boil  until  the  carbon  is  completely 
oxidized.  Filter  on  an  11 -cm.  filter  paper  and  wash  alternately 
with  2  per  cent  nitric  acid  and  hot  water  until  the  iron  is  all 
removed.  Heat  the  filtrate  to  boiling,  add  a  slight  excess  of 
potassium  permanganate  solution  and  boil  until  the  permanganate 
is  decomposed  and  manganese  dioxide  is  precipitated.  Add  a 
saturated  solution  of  sugar  or  other  reducing  agent  until  the 
manganese  dioxide  is  dissolved.  Cool  the  solution  to  80°  C., 


132  METALLURGICAL  ANALYSIS 

and  add  50  cc.  of  ammonium  molybdate  solution.  Shake  the 
flask  five  minutes,  filter,  and  proceed  according  to  Pemberton's 
method  (p.  86). 

MANGANESE  IN  IRON  AND  STEEL 

WALTERS'  COLOR  METHOD 

Reagents.     Nitric  acid  (sp.gr.  1.2). 

Ammonium  persulphate  (NELi) 28203. 

Solution  of  silver  nitrate.     (See  p.  90.) 

Mn  in  Iron  or  Steel.  Weigh  0.2  gm.  of  the  sample  and  trans- 
fer it  to  an  8-in.  test-tube  or  to  a  small  Erlenmeyer  flask.  Add 
from  a  pipette  10  cc.  of  dilute  nitric  acid.  Heat  on  a  water  bath 
until  the  steel  is  in  solution.  Add  0.5  gm.  of  moist  ammonium 
persulphate  and  heat  to  oxidize  the  combined  carbon.  If  the 
solution  is  not  clear,  filter  and  wash  the  residue  with  15  cc.  of 
silver  nitrate  solution.  If  filtering  is  not  necessary,  add  the 
silver  nitrate  solution  directly  to  the  solution  of  steel.  Add 
1  gm.  of  moist  ammonium  persulphate  and  heat  the  solution 
until  the  pink  permanganic  acid  color  develops.  Cool  and 
dilute  the  solution.  Transfer  it  to  a  colorimeter  and  match 
the  color  against  the  standard  that  has  been  treated  in  exactly 
the  same  manner.  (See  p.  44.) 

MANGANESE  IN  IRON  AND  STEEL 

TlTRATION    WITH    SODIUM    ARSENITE 

Reagents.     See  page  90. 

Mn  in  Iron  or  Steel.  Weigh  0.2  gm.  of  the  material  and  treat 
it  exactly  as  described  in  the  method  above  to  the  development 
of  the  pink  permanganic  acid  color.  Add  10  cc.  of  sodium 
chloride  solution  and  titrate  with  standard  sodium  arsenite  solu- 
tion to  the  disappearance  of  the  pink  color.  (See  p.  91.) 


MANGANESE  IN  STEEL  133 

MANGANESE  IN  STEEL 

SODIUM  BISMUTHATE  METHOD 

Reagents.     See  page  92. 

Weigh  1  gm.  of  steel  and  transfer  it  to  a  200-cc.  Erlenmeyer 
flask.  Add  50  cc.  of  dilute  nitric  acid  (1  :  3).  Heat  until 
the  steel  is  dissolved.  When  in  solution,  cool  and  add  0.5  gm. 
of  sodium  bismuthate  to  oxidize  carbonaceous  matter.  Heat 
until  the  pink  color  disappears  with  or  without  precipitation 
of  manganese  dioxide.  Add  sulphurous  acid  until  the  solu- 
tion clears.  Boil  out  the  excess  of  sulphurous  acid.  Cool  to 
15°  C.  and  add  an  excess  of  sodium  bismuthate  (2  or  3  gms.). 
Agitate  the  flask  for  several  minutes.  Add  50  cc.  of  dilute 
nitric  acid  (3  :  100)  and  proceed  according  to  the  method  on 
page  94. 

MANGANESE  IN  FERRO-MANGANESE  AND  SPIEGEL 

JULIAN'S  METHOD 

Reagents.    See  page  95. 

Weigh  0.25  gm.  of  ferro-manganese  and  transfer  it  to  a 
200-cc.  beaker.  Add  40  cc.  of  nitric  acid  (sp.gr.  1.2).  Cover 
and  boil  the  solution  almost  to  dryness.  Add  50  cc.  of  nitric 
acid  (sp.gr.  1.42).  Heat  to  boiling.  Take  off  the  cover  and 
add  potassium  chlorate,  a  little  at  a  time,  from  a  glass  spatula, 
until  the  green  fumes  suddenly  disappear  and  are  replaced  by 
white  fumes;  continue  boiling  for  three  or  four  minutes.  Cool, 
dilute  with  cold  water  to  about  200  cc.,  add  50  cc.  of  hydrogen 
peroxide  solution  and  titrate  with  standard  permanganate  solu- 
tion. See  the  method  on  page  95. 


134  METALLURGICAL  ANALYSIS 


MANGANESE  IN  STEELS  CONTAINING  CHROMIUM 
AND  TUNGSTEN 

WALTERS'  METHOD  * 

Reagents.    Dilute  sulphuric  add  (2:9). 

Solution  of  sodium  carbonate.     Dissolve  200  gms.  N 
10H2O  in  1  liter  of  water. 

Emulsion    of  zinc    oxide.     Suspend   ZnO   in  distilled   water 
by  shaking  in  a  flask. 

Sodium  bismuthate  NaBiOa. 

For  the  preparation  and  standardization  of  ferrous  sulphate 
and  potassium  permanganate  solutions  see  page  93. 

Mn  in  Steel.  Dissolve  2  gms.  of  the  steel  in  20  cc.  of  dilute 
sulphuric  acid  (2  :  9)  adding  enough  water,  from  time  to  time, 
to  keep  the  ferrous  sulphate  in  solution.  When  the  steel  is  dis- 
solved add  5  cc.  of  strong  nitric  acid.  Evaporate  until  the  sulphu- 
ric acid  fumes,  to  destroy  carbonaceous  matter.  Add  100  cc. 
of  water  and  boil  to  dissolve  ferric  sulphate.  Transfer  the 
solution  to  a  500-cc.  graduated  flask.  Add  sodium  carbonate 
solution  until  the  solution  of  steel  is  dark  in  color  and  the  pre- 
cipitate dissolves  slowly.  Add  emulsion  of  zinc  oxide,  a  little  at 
a  time,  and  shake  until  the  iron  and  chromium  are  precipitated. 
Dilute  to  the  mark  with  water.  Let  the  precipitate  settle. 
Decant  250  cc.  through  a  dry  filter  into  a  quarter-liter  graduated 
flask.  Transfer  it  to  a  half-liter  Erlenmeyer  flask  and  acidify 
with  25  cc.  of  nitric  acid  (sp.gr.  1.42).  Add  1  gm.  of  sodium 
bismuthate  and  shake  the  flask  several  minutes.  Let  the  residue 
settle.  Filter  through  asbestos  with  suction.  Wash  the  flask 
and  filter  with  water  acidulated  with  nitric  acid  until  the  washings 
are  free  from  the  pink  color  of  permanganic  acid.  Transfer  the 
filtrate  to  a  beaker,  add  a  measured  volume  of  standard  ferrous 
sulphate  solution  in  excess  of  the  permanganic  acid,  and  titrate 
the  excess  of  ferrous  sulphate  with  standard  potassium  per- 
*  Met.  and  Chem.  Eng.,  9,  224. 


TITANIUM  IN  IRON  135 

manganate  solution.  The  ferrous  sulphate  solution  should  be 
of  such  strength  that  1  cc.  is  equivalent  to  1  cc.  of  the  standard 
permanganate  solution. 

TITANIUM  IN  IRON 
WELLER'S  COLORIMETRTC  METHOD  * 

Reagents.     See  page  90. 

Ti  in  Iron.  Weigh  5  gm.  of  the  sample  and  transfer  it  to  a 
No.  4  beaker.  Add  50  cc.  of  strong  hydrochloric  acid,  cover  the 
beaker  and  heat  until  the  iron  is  completely  decomposed.  Filter, 
wash  with  hot  water,  and  ignite  the  filter  in  a  platinum  crucible. 
Cool,  add  a  few  drops  of  sulphuric  acid  and  enough  hydrofluoric 
acid  to  dissolve  the  silica.  When  the  silica  is  dissolved,  evaporate 
the  solution  to  complete  dryness. 

A  very  small  proportion  of  the  titanium  remains  in  solution  and 
passes  through  with  the  filtrate.  It  may  be  recovered  in  the 
following  way.  Dilute  the  filtrate  to  250  cc.,  add  strong  ammonia 
until  a  precipitate  appears  which  slowly  dissolves  upon  stirring. 
Add  2  per  cent  ammonia  water  until  a  slight,  permanent  precip- 
itate is  formed.  Add  15  cc.  of  dilute  hydrochloric  acid  (1  :  3). 
Stir  vigorously  to  dissolve  the  precipitate.  Add  100  cc.  or  more 
of  a  20  per  cent  solution  of  sodium  thiosulphate  and  stir  until  the 
iron  is  completely  reduced  and  free  sulphur  begins  to  separate. 
Boil  ten  minutes.  Let  the  precipitate  settle,  and  filter.  Wash 
with  2  per  cent  acetic  acid  solution  and  ignite  in  the  crucible 
containing  the  silica-free  titanium. 

Add  to  the  crucible  4  gm.  of  sodium  carbonate,  and  fuse. 
Cool  the  fusion  and  disintegrate  it  by  boiling  with  water. 
Filter  the  sodium  >titanate  from  the  solution  and  wash  with 
hot  water  in  which  has  been  dissolved  a  little  sodium  carbonate. 
Spread  out  the  filter  in  a  small  beaker.  Add  to  the  crucible 
in  which  the  fusion  was  made  a  little  dilute  sulphuric  acid  (1  :  3). 
*  Camp,  Met.  and  Chem.  Eng.,  10,  675. 


136  METALLURGICAL  ANALYSIS 

Boil  to  dissolve  off  any  adhering  titanium  and  pour  the  solution 
upon  the  filter  in  the  beaker.  Wash  the  crucible  with  hot  water, 
adding  the  washings  to  the  solution  in  the  beaker.  Heat  the 
beaker  to  dissolve  sodium  titanate.  Withdraw  the  filter  paper 
from  the  solution,  washing  it  carefully  with  hot  water. 

If  the  solution  contains  fibers  of  filter  paper,  filter,  and 
transfer  the  solution  to  a  Nessler  or  other  colorimeter  tube. 
Add  5  cc.  of  hydrogen  peroxide  and  compare  with  a  standard 
solution  in  the  manner  described  on  page  92. 

TITANIUM  IN  STEEL 
COLOR  METHOD 

Weigh  0.5  gm.  of  steel  (1  gm.  should  be  taken  if  it  contains 
less  than  0.05  per  cent  Ti)  and  transfer  to  a  large  test-tube  (10" 
XI")-  At  the  same  time  place  in  a  similar  test-tube  an  equal 
amount  of  a  steel  which  contains  no  titanium  and  add  to  it  a 
sufficient  quantity  of  soluble  ferro-titanium,  in  which  the  titanium 
has  been  determined,  to  bring  its  Ti  content  to  within  0.05  per 
cent  of  that  in  the  unknown  steel.  Add  to  each,  10  cc.  of  dilute 
sulphuric  acid  (1  :  3),  to  dissolve  the  steel. 

Add  5  cc.  of  concentrated  nitric  acid  to  oxidize  the  iron.  Boil 
off  the  red  fumes.  Cool,  add  5  cc.  of  hydrogen  peroxide  solu- 
tion, dilute  to  the  same  volume,  transfer  to  a  colorimeter  and 
compare  the  colors;  or  rinse  into  Eggertz  tubes  and  dilute  until 
the  two  have  the  same  color. 

Thymol  is  considered  by  Lehner  and  Crawford  *  to  be  more  deli- 
cate for  this  purpose  than  hydrogen  peroxide.  The  reagent  is  pre- 
pared by  dissolving  the  thymol  (CioHuO)  in  a  little  acetic  acid  and  then 
adding  sulphuric  acid.  The  solution  of  thymol  prepared  in  this  manner 
is  colorless  and  is  fairly  stable  if  kept  out  of  a  bright  light.  If  exposed 
to  a  bright  light  it  will  darken  in  a  few  hours. 

*  Eighth  International  Congress  of  Applied  Chemistry,  1,  p.  285. 


NICKEL  IN  STEEL  137 

NICKEL  IN  STEEL 

ETHER  METHOD 

Outline.  The  steel  is  dissolved  in  hydrochloric  acid,  the 
iron  oxidized  with  nitric  acid,  the  chloride  solution  is  shaken 
with  ether,  the  ether  solution  containing  most  of  the  iron  and 
the  aqueous  solution  containing  the  nickel  are  allowed  to  separate 
in  a  separating  funnel  and  the  aqueous  solution  is  drawn  off. 
The  iron  and  manganese  are  precipitated  and  filtered  from  the 
aqueous  solution.  The  nitrate  is  acidified  and  if  copper  is 
present  it  is  precipitated  with  hydrogen  sulphide  and  the  solu- 
tion filtered,  the  filtrate  is  made  ammoniacal,  the  nickel  pre- 
cipitated with  hydrogen  sulphide,  filtered  from  the  solution, 
burnt,  and  weighed  as  NiO. 

Reagents.     Dilute  hydrochloric  acid,  (1:1). 

Ether,  C2H5-O-C2H5. 

Bromine  water;  water  saturated  with  Br. 

Hydrogen  Sulphide.  Generate  H2S  by  adding  dilute  HC1 
(sp.gr.  1  :  1)  to  FeS  in  a  gas  generator.  (Fig.  53,  p.  64.) 

Acetic  acid.     90  per  cent,  CH3  •  COOH. 

Ni  in  Steel.  Dissolve  2  gm.  of  steel  in  30  cc.  of  dilute  hydro- 
chloric acid  (1:1).  Add  2  cc.  of  strong  nitric 
acid  to  oxidize  the  iron.  Evaporate  to  10  cc. 
Cool  and  pour  the  solution  into  a  150-cc.  separa- 
tory  funnel  with  short  stem  (Fig.  72) .  Wash  out 
the  beaker  with  dilute  hydrochloric  acid  (1  :  1), 
using  a  small  amount  at  a  time,  and  adding  the 
washings  to  the  funnel.  Do  not  let  the  volume 
exceed  40  cc.  Cool  and  add  50  cc.  of  ether. 

Place    the    stopper  in    the    funnel    and   shake  ^ato  ~Fun" 
gently  at  first.     Keep  the  funnel  cool  by  holding 
it  under  running  water.      If    allowed   to   become 
hot   the   ether   would    reduce   some   ferric   chloride  to   ferrous 
chloride. 


138  METALLURGICAL  ANALYSIS 

The  greater  part  of  the  ferric  chloride  is  taken  up  by  the  ether, 
leaving  the  nickel,  cobalt,  manganese,  aluminum,  and  copper,  and  a 
little  of  the  iron,  in  the  original  solution. 

Set  the  funnel  in  an  upright  position  and  let  the  ether  and 
aqueous  solutions  separate.  Complete  separation  is  indicated 
by  a  sharp  line  between  them.  Take  out  the  stopper,  open  the 
tap,  and  draw  off  the  aqueous  solution,  leaving  the  ether  in  the 
funnel.  Add  5  cc.  of  dilute  hydrochloric  acid  (1  :  1)  to  the  ether 
in  the  funnel. 

Only  a  small  quantity  of  acid  is  used,  because  it  takes  some  iron 
out  of  the  ether  solution. 

Shake  again  and  separate  as  before. 

If  the  steel  is  high  in  nickel,  wash  a  second  time  with  hydro- 
chloric acid. 

Discard  the  ether  solution,  which  contains  most  of  the  ferric 
chloride.  Cover  the  beaker  containing  the  aqueous  solution 
and  boil  off  the  -ether,  taking  care  that  it  does  not  take  fire. 
Dilute  to  200  cc.,  add  3  cc.  of  bromine  water  to  precipitate 
manganese,  add  a  decided  excess  of  ammonia,  and  boil  to  pre- 
cipitate ferric  hydrate.  Filter,  wash  once  with  water,  and  wash 
the  precipitate  back  into  the  beaker.  Redissolve  the  precip- 
itate in  hydrochloric  acid,  add  bromine  water,  and  precipitate 
again  with  ammonia. 

Filter,  combine  the  filtrates,  and  boil  off  the  ammonia.  Make 
the  solution  distinctly  acid  with  hydrochloric  acid. 

If  copper  is  present,  pass  hydrogen  sulphide  through  the  solu- 
tion and  filter  the  precipitated  copper  sulphide.  Evaporate  the 
filtrate  to  100  cc.  and  add  ammonia  until  it  is  just  alkaline. 
Saturate  the  hot  solution  with  hydrogen  sulphide  to  precipitate 
the  sulphides  of  nickel  and  manganese.  Neutralize  the  solu- 
tion with  acetic  acid  and  then  add  an  excess  of  4  cc.  to  dis- 
solve manganese  sulphide.  Filter  off  the  nickel  sulphide,  wash 
well  with  hot  water,  and  ignite  it  in  an  open,  porcelain  crucible. 


NICKEL  IN  STEEL  139 

Burn  the  paper  at  as  low  heat  as  possible  and  then  heat  a  few 
minutes  at  the  highest  temperature.  Cool  in  a  desiccator  and 
weigh  as  NiO.  The  factor  for  nickel  in  NiO  is  0.78576. 

If,  in  burning,  any  nickel  is  reduced  to  the  metallic  state, 
reoxidize  it  with  a  few  drops  of  nitric  acid,  evaporate  the 
excess  of  acid,  heat  to  a  high  temperature,  and  weigh. 

NICKEL  IN  STEEL 

POTASSIUM  CYANIDE  METHOD* 

Reagents.  Silver  nitrate  solution.  Dissolve  1  gm.  of  AgNOs 
in  1  liter  of  water. 

Potassium  iodide  solution.  Dissolve  20  gms.  of  KI  in  water 
and  dilute  to  1  liter. 

Standard  solution  of  nickel.  This  solution  may  be  made  by 
dissolving  pure  metallic  nickel,  or  a  pure  salt  of  nickel.  A 
convenient  strength  is  about  0.0005  gm.  Ni  per  cubic  centi- 
meter. 

Standard  solution  of  potassium  cyanide.  Dissolve  4  gms. 
KCN  in  1  liter  of  water. 

The  cyanide  solution  is  not  permanent  and  must  be  stand- 
ardized frequently.  It  is  standardized  in  the  following  way: 

Take  50  cc.  of  the  standard  nickel  solution,  dilute  it  to  100 
cc.,  and  add  20  cc.  of  hydrochloric  acid.  Neutralize  with  ammonia 
and  add  1  cc.  of  ammonia  in  excess.  Add  5  cc.  each  of  the  silver 
nitrate  solution  and  the  potassium  iodide  solution. 

AgN03+KI=AgI+KN03. 

The  silver  iodide  renders  the  solution  turbid. 
Titrate  with  the  potassium  cyanide  solution  until  the  solu- 
tion clears. 

NiCl2+4KCN  =K2Ni(CN)4+2KCl. 

*  Deniges,  Chem.  News,  69,  p.  42.     Moore,  Chem.  News,  72,  p.  92. 


140  METALLURGICAL  ANALYSIS 

When  the  reaction  with  the  nickel  is  complete,  the  silver 
iodide  is  dissolved  by  the  excess  of  potassium  cyanide. 

2KCN+AgI  =KAg(CN)2+KI. 

A  blank  should  be  run,  leaving  out  the  nickel  and  includ- 
ing all  the  reagents  in  the  quantities  given  above  to  learn  how 
much  potassium  cyanide  is  required  to  dissolve  the  silver  iodide. 
The  quantity  of  potassium  cyanide  thus  determined  should 
be  deducted  from  all  tit  rations. 

Ni  in  Steel.  Weigh  2  gms.  of  steel  and  treat  it  according  to 
the  ether  method  for  nickel  (p.  137)  until  the  copper  sulphide 
has  been  filtered  from  the  solution.  Evaporate  the  nitrate  to 
100  cc.  Neutralize  with  ammonia  and  add  1  cc.  in  excess. 
Then  add  5  cc.  each  of  the  silver  and  potassium  iodide  solutions 
and  titrate  with  standard  potassium  cyanide  solution. 

NICKEL  IN  STEEL 

DlMETHYLGLYOXIME    METHOD* 

Reagents.     Hydrofluoric  acid,  HF. 

Tartaric  acid,  C4H60e. 

Dimethylglyoxime  solution.  Dissolve  1  gm.  of  dimethyl- 
glyoxime(CH3-C-(  :  N-OH)C(  :  N-OH)CH3)  in  100  cc.  of  alco- 
hol, (C2H60). 

Ni  in  Steel.  Dissolve  1  gm.  of  steel  in  25  cc.  of  hydrochloric 
acid.  Add  a  few  cubic  centimeters  of  nitric  acid  to  oxidize 
the  iron.  Boil  out  the  chlorine  and  most  of  the  hydrochloric 
acid.  If  silica  should  be  precipitated  in  the  solution,  add  a  little 
hydrofluoric  acid.  When  solution  is  complete,  add  about  3 
gms.  of  tartaric  acid  and  300  cc.  of  water.  Make  the  solution 
slightly  ammoniacal. 

If  iron  is  precipitated,  acidify  with  hydrochloric  acid,  heat  to  dis- 
solve the  precipitate,  and   add  more  tartaric  acid.    When  the  tartaric 
acid  is  dissolved  add  ammonia  to  render  the  solution  alkaline. 
*  O.  Brunck.     Stahl  u.  Eisen,  28,  331. 


CHROMIUM  AND  VANADIUM  IN  STEEL    '  141 

If  the  iron  remains  in  solution,  heat  nearly  to  boiling,  and 
add  20  cc.  of  dimethylglyoxime  solution.  Let  the  solution  stand 
for  fifteen  minutes  at  a  temperature  of  between  80°  and  90°  C. 

2C4H8N202+NiCl2=C8H14N404Ni+2HCL 

If  the  flocculent  precipitate  of  nickel  stands  long  in  the  mother 
liquor  at  a  high  temperature,  it  becomes  minutely  crystalline  and  is 
filtered  with  great  difficulty. 

Filter  while  hot  in  a  Gooch  crucible.  Wash  with  hot  water 
until  it  comes  through  colorless.  Dry  forty-five  minutes  at  a 
temperature  of  110°  to  120°  C.  and  weigh.  The  dried  precipitate 
contains  20.325  per  cent  Ni. 

CHROMIUM  AND  VANADIUM  IN  STEEL 

Outline.  The  steel  is  dissolved  in  sulphuric  and  nitric  acids, 
the  chromium  and  vanadium  are  oxidized  with  potassium  per- 
manganate, and  the  resulting  manganese  dioxide  filtered  from 
the  solution.  After  adding  sulphuric  acid  to  the  filtrate  the 
chromium  is  titrated  with  a  standard  solution  of  ferrous  ammonium 
sulphate.  The  excess  of  ferrous  ammonium  sulphate  is  titrated 
back  with  standard  potassium  permanganate  solution,  an  indi- 
cator is  added  and  the  titration  with  standard  ferrous  ammonium 
sulphate  solution  is  continued  for  the  vanadium.* 

Reagents.    Dilute  sulphuric  acid  (1  :  3). 

Nitric  acid  (sp.gr.  1.2);  add  40  cc.  HN03  (sp.gr.  1.42)  to  65 
cc.  of  water. 

A  strong  solution  of  potassium  permanganate  for  oxidizing 
chromium  and  vanadium;  20  gm.  of  KMn04  in  a  liter  of  water. 

Standard  potassium  permanganate  solution;  2.83  gm.  of 
KMn04  per  liter.  (See  p.  51.) 

Standard  solution  of  ammonium  ferrous  sulphate;    35.09  gm. 
of  (NH4)2S04-FeS04+6H2O  dissolved  in  300  cc.  of  dilute  sul- 
phuric acid  (1:3)  and  diluted  to  1  liter  with  water. 
*  Johnson,  "  Chem.  Anal,  of  Special  Steels,"  p,  8, 


142  METALLURGICAL  ANALYSIS 

This  solution  should  be  standardized  against  the  perman- 
ganate solution  and  corrected,  if  necessary,  to  be  of  exactly 
equal  value. 

This  solution  will  be  equivalent  to  about  0.001555  gm.  of 
chromium,  but  it  should  be  standardized  for  chromium  by  tak- 
ing 2  gms.  of  steel  in  which  the  chromium  has  been  determined 
(or  a  steel'  free  from  Cr  and  adding  a  weighed  quantity  of  pure 
K2O207)  and  treating  it  exactly  according  to  the  method  given 
below. 

The  solution  should  be  standardized  in  a  similar  way  for 
vanadium.  Its  value  in  vanadium  should  be  about  0.00456. 

Solution  of  potassium  ferricyanide.  Dissolve  5  gms.  of 
K3Fe(CN)6m  130  cc.  of  water. 

Cr  and  V  in  Steel.  Weigh  2  gm.  of  steel,  transfer  it  to  a 
600-cc.  beaker,  and  add  30  cc.  of  dilute  sulphuric  acid  (1  :  3) 
and  20  cc.  of  water.  Heat;  when  the  first  vigorous  reaction 
is  over,  add  60  cc.  of  dilute  nitric  acid  (sp.gr.  1.2)  to  complete 
the  solution  and  to  oxidize  the  iron.  After  it  is  in  solution, 
boil  two  minutes  and  add  200  cc.  of  water.  From  a  small  pipette 
add  potassium  permanganate  solution,  a  little  at  a  time,  until 
there  is  a  slight  precipitate  of  Mn02,  which  does  not  dissolve 
after  boiling  twenty  minutes. 

Chromium  is  converted  to  Cr03  and  the  vanadium  to  V205. 

Remove  the  beaker  from  the  heat  and  place  it  in  a  dish  of 
cold  water.  Filter  by  suction  on  asbestos  which  has  been  pre- 
viously washed  with  nitro-hydrochloric  acid,  and  finally  washed 
well  with  water.  Wash  the  residue  on  the  filter  15  times  with 
very  dilute  sulphuric  acid  (1  :  600).  Transfer  the  filtrate  and 
washings,  the  volume  of  which  should  be  about  300  cc.,  to  the 
600-cc.  beaker.  Add  30  cc.  of  dilute  sulphuric  acid  and  titrate 
with  a  standard  solution  of  ferrous  ammonium  sulphate  until 
the  solution  loses  its  brown  tint  and  becomes  practically  colorless, 
if  the  steel  has  less  than  1  per  cent  of  chromium;  and  if  higher 


CHROMIUM  AND  VANADIUM  IN   STEEL  143 

in  chromium  (2  to  6  per  cent),  titrate  until  the  chrome  green 
no  longer  grows  darker. 

2Cr03+6FeS04+6H2S04=6H20+3Fe2(S04)3+Cr2<S04)3. 

Then  add  2  or  3  cc.  more  of  the  ferrous  ammonium  sulphate 
solution,  to  ensure  the  reduction  of  all  of  the  chromium.  Read 
the  burette  and  titrate  back  with  standard  permanganate  solu- 
tion until  a  faint  pink  persists  after  stirring  thirty  seconds.  The 
pink  color  can  be  detected  in  the  chrome  green  solution  after  a 
little  practice.  The  equivalent  of  the  permanganate  titration, 
in  terms  of  ferrous  ammonium  sulphate,  deducted  from  the 
total  volume  of  ferrous  ammonium  sulphate  solution  added, 
represents  the  quantity  of  ammonium  ferrous  sulphate  solution 
required  to  reduce  the  chromium. 

V  in  Steel.  The  solution  of  steel  in  which  the  chromium  has 
been  titrated  according  to  the  method  above  may  be  used  for  the 
estimation  of  vanadium.  After  titrating  back  with  permanganate 
solution  for  the  determination  of  chromium,  add,  from  a  dropper, 
12  drops  of  potassium  ferricyanide  solution  (5  gms.  KsFe(CN)6 
in  130  cc.  of  water).  This  gives  the  solution  a  brown  color. 
Now  titrate  with  ferrous  ammonium  sulphate  solution  to  a 
green  color,  free  from  yellow  tints.  Do  not  titrate  to  blue. 


If  much  chromium  is  present,  titration  continues  until  the  green 
color  begins  to  darken. 

If  as  much  as  0.5  per  cent  of  copper  is  present,  it  produces  a  light 
yellow  cloud  of  copper  ferricyanide  when  the  indicator  is  added.  In 
such  steels  the  copper  should  be  precipitated  with  ferricyanide  before 
the  Mn02  is  filtered  from  the  solution;  both  are  then  removed  at  the 
same  time. 

Run  a  blank  on  a  steel  without  vanadium,  and  correct  all  titrations 
accordingly.  The  blank  is  from  0.3  cc.  to  0.4  cc.  if  no  chromium  is  pres- 
ent; from  0.7  cc.  to  0.9  cc.  if  the  steel  has  3  per  cent  chromium;  and 
from  1  cc.  to  1.2  cc.  if  there  is  4  per  cent  chromium. 

If  the  steel  is  high  in  chromium  and  tungsten,  digest  the  drillings 


144  METALLURGICAL  ANALYSIS 

until  the  tungstic  acid  is  bright  yellow  before  adding  potassium  per- 
manganate. Then  add  enough  potassium  permanganate  to  make  the 
tungstic  acid  chocolate  color  by  the  admixture  of  Mn02. 

VANADIUM  IN  STEEL 

VOLUMETRIC  METHOD 

Reagents.    Standard  permanganate  solution.     (See  p.  51.) 

The  permanganate  solution  is  standardized  for  vanadium 
by  weighing  2  gm.  of  a  steel  in  which  the  vanadium  is  known 
and  treating  it  according  to  the  method  given  below. 

Dilute  sulphuric  acid  (1  :  2). 

Zinc  oxide,  ZnO. 

Zinc  hydroxide,  Zn(OH)2  suspended  in  water. 

Sodium  hydroxide,  (NaOH) 

Potassium  nitrate,  (KNOs). 
'  Manganese  chloride;  a  saturated  solution  of  MnCb. 

V  in  Steel.  Dissolve  2  gms.  of  steel  in  60  cc.  of  dilute  sul- 
phuric acid  and  200  cc.  of  water.  When  in  solution  neutralize 
the  greater  part  of  the  acid  with  zinc  oxide.  See  that  all  of  the 
zinc  oxide  is  dissolved.  Complete  the  neutralization  by  adding 
precipitated  zinc  hydroxide  in  water  until  some  undissolved 
hydroxide  remains.  Heat,  filter,  and  wash  with  hot  water. 
The  precipitate  contains  the  whole  of  the  vanadium  and  only 
a  small  amount  of  iron.  Place  the  filter  with  the  precipitate 
in  a  nickel  crucible,  burn  the  paper,  and  heat  the  precipitate 
to  redness.  Add  to  the  burnt  precipitate  a  few  grams  of  sodium 
hydroxide  and  a  little  potassium  nitrate. 

V,06+4NaOH  =Na4V207+2H20. 

Extract  with  water.  Filter  and  precipitate  the  vanadium  from 
the  filtrate  with  manganese  chloride  solution. 

Na4V207+2MnCl2  =  Mn2V207+4NaCl. 


VANADIUM  IN  STEEL  145 

Filter;  dissolve  the  precipitate  in  hydrochloric  acid.  Add 
10  cc.  of  sulphuric  acid,  heat,  and  titrate  hot  with  standard 
potassium  permanganate  solution. 

5V204+2KMn04+3H2S04=5V206+K2S04+2MnS04+3H20. 
VANADIUM  IN  STEEL 

COLORIMETRIC    METHOD* 

Reagents.    Nitric  add  (sp.gr.  1.2). 

Ammonium  persulphate,  (NILt) 28203. 

Phosphoric  acid,  H3PO4  (sp.gr.  1.30). 

Hydrogen  peroxide,  H202. 

Standard  vanadium  solution.  Dissolve  1  gm.  ammonium 
vanadate  (NH^VOs)  in  water.  Add  20  cc.  dilute  sulphuric 
acid,  (1:3),  dilute  to  1  liter  and  shake  well.  To  200  cc.  of 
this  solution  add  25  cc.  of  dilute  sulphuric  acid  (1:3),  and  heat 
to  boiling.  Add  30  cc.  sulphurous  acid  (H^SOs),  and  boil  to 
expel  the  excess  of  SO2.  Titrate  the  hot  solution  with  standard 
permanganate  solution  and  calculate  the  vanadium  content. 

V205+H2S03  =  V204+H2S04. 
5V2O4+2KMn04+3H2S04=5V205+K2S044-2MnS04+3H2O. 

Dilute  a  portion  of  the  ammonium  vanadate  solution  remain- 
ing, so  that  1  cc.  will  contain  0.0001  gm.  vanadium. 

V  in  Steel.  Weigh  0.25  gm.  of  the  sample  and  an  equal 
amount  of  a  steel  containing  no  vanadium,  and  having  about 
the  same  content  of  carbon.  Place  each  in  a  large  test-tube. 
Add  to  each  4  cc.  of  dilute  nitric  acid  and  heat  in  a  water-bath 
until  the  steel  is  dissolved.  To  the  clear  solution  add  about 
0.3  gm.  of  ammonium  persulphate.  Heat  until  the  evolution 
of  gas  ceases.  Cool  and  add  to  the  solution  containing  no 
vanadium  1  cc.  of  the  standard  vanadium  solution.  Add  to 

*  Slawik,  Chem.  Zeit.,  34,  p.  648. 


146  METALLURGICAL  ANALYSIS 

both  4  cc.  of  phosphoric  acid  and  4  cc.  of  hydrogen  peroxide. 
If  the  color  of  the  standard  is  much  lighter  than  that  of  the 
unknown,  prepare  a  stronger  solution  of  the  standard  and  com- 
pare in  a  colorimeter  or  transfer  to  Eggertz  tubes  and  dilute 
until  the  colors  match. 

TUNGSTEN  IN  STEEL 

Outline.  The  steel  is  dissolved  in  nitric  and  hydrochloric 
acids,  the  solution  evaporated  to  a  small  volume,  diluted,  and 
filtered  from  the  oxides  of  tungsten  and  silicon.  The  filter  is 
burnt  in  a  platinum  crucible,  the  residue  treated  with  hydro- 
fluoric and  sulphuric  acids,  and  evaporated  to  dryness  to  remove 
the  silica.  The  residue  of  WOs  contaminated  with  a  little  ferric 
oxide  is  weighed,  after  which  it  is  fused  with  sodium  carbonate, 
treated  with  water,  the  ferric  oxide  filtered  from  the  solution, 
burnt,  and  weighed;  and  this  weight  is  deducted  from  the  first 
weight  of  combined  oxides.* 

Reagents.     Hydrofluoric  acid,  HF. 

Dilute  sulphuric  acid  (1  :  20). 

Sodium  carbonate,  Na2COs. 

W  in  Steel.  Weigh  2  gms.  of  steel.  Transfer  it  to  a  por- 
celain casserole,  and  treat  it  with  a  mixture  of  30  cc.  of  concen- 
trated nitric  acid  and  30  cc.  of  concentrated  hydrochloric  acid. 
Heat  and  agitate  until  the  steel  is  in  solution  and  the  precipi- 
tated tungstic  acid  has  a  bright  yellow  color. 

Do  not  leave  a  glass  rod  in  the  solution,  since  tungstic  acid  attacks 
glass  in  hot  acid  solution. 

Take  off  the  cover  and  evaporate  the  solution  to  20  cc. 
Dilute  with  100  cc.  of  water,  stir  well,  and  remove  the  stirring 
rod.  Heat  to  boiling  and  hold  at  the  boiling-point  for  half 
an  hour.  Add  a  little  paper  pulp  and  filter.  Wash  with  dilute 

*  Johnson,  "  Anal,  of  Special  Steels,"  p.  74. 


TUNGSTEN  IN  STEEL  147 

hydrochloric   acid    (1  :  20)    until   the   precipitate   is   free   from 
iron,  and  then  wash  with  water. 

Test  with  potassium  or  ammonium  sulphocyanate. 

Ignite  the  precipitate  in  a  platinum  crucible  and,  if  the 
SiC>2  is  to  be  determined,  weigh  as  WO3+Si02-f  Fe2O3.  Add 
a  few  drops  of  sulphuric  acid  and  10  cc.  of  hydrofluoric  acid. 
Evaporate  to  sulphuric  acid  fumes  and  then  drive  off  the  sul- 
phuric acid  by  heating  the  crucible  from  the  top.  Heat  at  a 
high  temperature.  Cool  and  weigh  as  W03+Fe203.  Add  5 
gms.  of  sodium  carbonate  and  fuse  twenty  minutes.  Dissolve 
in  a  casserole  with  water.  Filter  the  iron  from  the  solution, 
wash  with  water  to  free  the  precipitate  from  sodium  (about 
40  washings  should  be  sufficient).  Ignite  in  a  platinum  crucible 
and  weigh.  Deduct  the  weight  from  the  combined  weight  of 
W03+Fe2O3.  The  difference  is  the  weight  of  WO3.  The 
factor  for  W  in  WO3  is  0.7931. 

W  in  the  Presence  of  Cr.  If  the  steel  contains  chromium, 
the  difference  between  the  last  two  weights  above  will  be 
W03+Cr2O3.  Therefore,  to  determine  the  percentage  of  tung- 
sten, the  quantity  of  chromium  which  is  in  the  filtrate  with  the 
tungsten  is  determined  by  the  method  described  on  page  141, 
for  the  determination  of  chromium  in  steel.  That  is,  add 
sulphuric  acid  to  the  nitrate  from  the  ferric  oxide  until  the  solu- 
tion is  acid  and  boil  it  with  a  slight  excess  of  potassium  per- 
manganate. Filter,  cool,  and  dilute  to  300  cc.,  add  30  cc.  of 
dilute  sulphuric  acid,  and  titrate  with  standard  ferrous  ammo- 
nium sulphate.  The  chromium  found  is  calculated  to 
and  deducted  from  the  combined  weight  of 


148  METALLURGICAL  ANALYSIS 

MOLYBDENUM  IN  STEEL 
LEAD  MOLYBDATE  METHOD* 

Reagents.  Solution  of  sodium  hydroxide.  Dissolve  80  gms. 
NaOH  in  water  and  dilute  to  1  liter. 

Methyl  orange.  Dissolve  1  gm.  CuH^NsSOaNa  in  water 
and  dilute  to  1  liter. 

Lead  acetate  solution.  A  saturated  solution  of  Pb  (02^02)  2 
+3H20  in  water. 

Ammonium  acetate,  (NH4C2H3O2). 

Mo  in  Steel.  Weigh  2  gms.  of  steel,  dissolve  it  in  40  cc. 
of  hydrochloric  acid,  oxidize  by  adding  5  cc.  of  nitric  acid. 
Nearly  neutralize  the  acids  by  adding  sodium  hydroxide  solu- 
tion. If  there  is  a  precipitate  (WOa  or  MoOs),  filter  through 
a  little  paper  pulp,  transfer  the  pulp  to  a  flask,  and  add  100 
cc.  of  sodium  hydroxide  solution.  Heat  nearly  to  boiling, 
shake  vigorously,  and  add,  through  a  funnel,  while  shaking, 
the  hot  filtrate.  Dilute  the  solution  to  500  cc.  in  a  graduated 
flask.  Filter  off  250  cc.  Add  a  drop  of  methyl  orange  and 
hydrochloric  acid  to  decided  acidity.  Then  add  20  cc.  of  lead 
acetate  solution  (if  the  steel  has  more  than  5  per  cent  Mo, 
add  more  of  the  precipitant)  and  a  sufficient  amount  of 
ammonium  acetate  to  combine  with  all  the  hydrochloric  acid 
and  leave  an  excess.  Heat  to  boiling.  Let  the  precipitate 
settle,  filter,  wash  with  hot  water,  ignite  at  a  low  red  heat, 
and  weigh  as  PbMoCU.  The  factor  for  Mo  in  PbMoO4  is 
0.2615. 

If  the  steel  contains  tungsten,  the  lead  molybdate  will  not  be 
pure,  but  will  have  mixed  with  it  lead  tungstate  (PbWCU).  To 
separate  them,  dissolve  the  ignited  precipitate  in  hydrochloric 
acid.  Add  a  few  drops  of  nitric  acid  and  evaporate  nearly  to 
dryness.  Add  200  cc.  dilute  hydrochloric  acid  (1  :  4).  Boil, 

*  Chatard,  Chem.  News.  24,  p.  175. 


MOLYBDENUM  IN  STEEL  149 

and  filter  off  WOs.  Reprecipitatc  the  molybdenum  from  the 
filtrate  with  lead  acetate,  as  in  the  method  just  described.  Filter, 
burn  and  weigh  it. 

MOLYBDENUM  IN  STEEL 
WEIGHING  AS  MoOs 

Reagents.     Dilute  nitric  acid  (2:3). 

Tartaric  acid,  C^eOe. 

Dilute  sulphuric  acid  (1  :  3). 

Hydrogen  sulphide,  H^S  from  a  generator.    (See  Fig.  53,  p.  64.) 

Mo  in  Steel.  Dissolve  2  gms.  of  steel  in  dilute  nitric  acid 
(2:3).  Cool:  and  add  3  or  4  gms.  of  tartaric  acid  (a  sufficient 
quantity  to  keep  the  iron  in  solution,  after  rendering  alkaline 
with  ammonia). 

Add  ammonia  until  slightly  alkaline.  Dilute  to  700  cc. 
Saturate  with  hydrogen  sulphide  by  passing  a  current  of  the 
gas  through  the  solution.  Add  dilute  sulphuric  acid  (1:3), 
drop  by  drop,  until  the  solution  is  slightly  acid. 

When  the  solution  becomes  acid,  the  reddish  brown  MoSs 
forms  and  settles  readily. 

Add  a  little  paper  pulp  and  pass  H^S  through  the  solution 
thirty  minutes.  Filter  and  wash  quickly  with  hydrogen  sul- 
phide water  containing  2  drops  of  sulphuric  acid  per  liter.  Burn 
off  the  paper  in  a  platinum  crucible  and  roast  the  MoSs  to  MoOs 
at  a  very  low  red  heat. 

MoOs  is  volatile  at  a  strong  red  heat. 

Cool  in  a  desiccator  and  weigh  Mof  3.  The  factor  for  Mo 
in  Mo03  is  0.6666. 

MOLYBDENUM  IN  MOLYBDENUM  POWDERS 

Weigh  0.5  gm.  of  the  powder.  Treat  with  aqua  regia.  Dilute 
and  filter.  Burn  the  filter  and  fuse  the  residue  with  sodium 
carbonate  and  a  small  quantity  of  sodium  nitrate.  Dissolve  the 


150  METALLURGICAL  ANALYSIS 

fusion  in  dilute  hydrochloric  acid  and  add  it  to  the  main  solu- 
tion. Evaporate  the  solution  to  dry  ness.  Dissolve  the  residue 
in  dilute  hydrochloric  acid.  Filter  and  precipitate  the  molybde- 
num from  the  filtrate  with  a  solution  of  lead  acetate  and  pro- 
ceed according  to  the  method  given  on  page  148. 

COPPER  IN  STEEL 

GRAVIMETRIC  METHOD 

Reagents.    Dilute  sulphuric  acid  (1  :  3). 

Sodium  thiosulphate,  Na2S2O3+5H2O. 

Weigh  5  gms.  (or  more  if  low  in  copper) .  Transfer  it  to  a  500-cc. 
beaker,  add  50  cc.  dilute  of  sulphuric  acid  (1:3),  and  heat  to 
dissolve. 

If  the  steel  does  not  readily  dissolve  in  sulphuric  acid,  dissolve  it  in 
dilute  nitric  acid  (2  :  3).  Add  20  cc.  of  sulphuric  acid  (1:1)  and 
evaporate  until  the  sulphuric  acid  fumes. 

Dilute  the  solution  to  400  cc.  with  hot  water.  Add  6  gms. 
of  sodium  thiosulphate  and  boil  until  the  cloudiness  due  to  the 
precipitated  sulphur  clears. 

Hydrogen  sulphide  may  be  used  as  the  precipitant  instead  of  sodium 
thiosulphate. 

Filter,  wash  with  hot  water,  and  ignite  the  filter  and  residue 
in  a  porcelain  crucible  over  a  Bunsen  burner;  cool  in  a  desic- 
cator and  weigh  CuO. 

2CuS+302  =2CuO+2S02. 

The  temperature  should  not  be  raised  high  enough  to  melt  the 
copper  oxide. 

The  precipitate  is  usually  contaminated  with  a  little  of  the 
oxides  of  iron,  silicon,  and  possibly  chromium. 

The  impurities  may  be  removed  as  follows:  Dissolve  the 
weighed  precipitate  in  a  little  strong  hydrochloric  acid.  Dilute, 


COPPER  IN  STEEL  151 

add  an  excess  of  ammonia,  filter,  burn,  and  weigh.  Deduct 
the  weight  from  the  weight  of  the  combined  oxides.  The  dif- 
ference represents  the  weight  of  copper  oxide.  The  factor  for 
C  in  CuO  is  0.7989. 

COPPER  IN  STEEL 

VOLUMETRIC  METHOD 

Weigh  the  steel  and  proceed  according  to  the  method  above 
until  the  copper  sulphide  is  filtered  from  the  solution  and  washed. 
Dissolve  the  copper  sulphide  in  warm  dilute  nitric  acid  and 
proceed  according  to  one  of  the  volumetric  methods  for  copper 
in  ore.  (See  p.  168.) 

NITROGEN  IN  STEEL 

Outline.  The  steel  is  dissolved  in  hydrochloric  acid,  the 
solution  distilled  with  sodium  hydroxide  solution,  the  dis- 
tillate containing  the  nitrogen  is  treated  with  Nessler  reagent  and 
compared  with  a  standard  solution  similarly  treated.* 

Reagents.  Hydrochloric  acid  (sp.gr.  1-1)  free  from  ammonia; 
or  the  ammonia  in  the  acid  may  be  determined  and  the  correc- 
tion made  for  each  estimation  of  nitrogen. 

To  prepare  ammonia-free  hydrochloric  acid,  distil  strong 
hydrochloric  acid  from  a  flask  provided  with  a  separatory  funnel 
and  delivery  tube,  to  which  has  also  been  added  some  strong  sul- 
phuric acid,  free  from  nitrous  acid.  Pass  the  HC1  gas,  which 
distils  off,  through  a  small  wash  bottle  containing  dilute  hydro- 
chloric acid  (1  :  1)  and  finally  into  distilled  water  free  from 
ammonia. 

If  the  ordinary  distilled  water  contains  ammonia,  redistil, 
and  reject  the  first  distillate,  which  will  contain  the  ammonia. 

Solution  of  sodium  hydroxide.  Dissolve  300  gms.  of  fused 
NaOH  in  500  cc.  of  distilled  water.  Heat  for  twenty-four  hours 
*  Allen,  Chem.  News,  41,  231. 


152  METALLURGICAL  ANALYSIS 

at  50°  C.  in  contact  with  a  copper-zinc  couple,  prepared  by  rolling 
together  about  15  cm.2  each  of  zinc  and  copper  foil.  The  copper- 
zinc  couple  decomposes  nitrates,  so  that  ammonia  will  be  expelled 
in  the  first  distillation.* 

Nessler  reagent.  Dissolve  35  gms.  potassium  iodide  in 
about  50  cc.  of  water.  Add  concentrated  solution  of  mercuric 
chloride,  little  by  little,  shaking,  until  there  is  a  permanent  red 
precipitate.  Filter  and  add  to  the  filtrate  120  gms.  of  sodium 
hydroxide  dissolved  in  about  200  cc.  of  water.  Dilute  to  1  liter. 
Add  to  this  5  cc.  of  a  saturated  solution  of  mercuric  chloride  in 
water.  Mix  thoroughly,  let  the  precipitate  settle,  and  decant 
the  clear  solution  into  a  glass-stoppered  bottle. 

Standard  solution  of  ammonia.  Dissolve  in  1  liter  of  water 
0.0382  gm.  NH4C1  which  has  been  dried  at  100°  C.  One  cubic 
centimeter  will  contain  0.01  mgm.  of  nitrogen. 

N  in  Steel.  Place  40  cc.  of  the  sodium  hydroxide  solution, 
which  has  been  prepared  with  the  copper-zinc  couple,  into  a 
1500-cc.  Erlenmeyer  distilling  flask,  provided  with  a  separatory 
funnel  and  a  condenser.  Add  500  cc.  of  water  and  about  25 
gms.  of  tin  foil,  to  prevent  bumping,  and  distil  until  the  Nessler 
reagent  gives  no  reaction  with  the  distillate. 

While  this  is  going  on,  weigh  3  gms.  of  steel  free  from  oil 
and  dissolve  it  in  30  cc.  of  ammonia-free  hydrochloric  acid. 
Transfer  the  solution  to  the  bulb  of  the  separatory  funnel  and  when 
the  soda  solution  is  free  from  ammonia  drop  the  ferrous  chloride 
solution  very  slowly  into  the  boiling  solution  in  the  flask  and 
collect  the  distillate  in  a  glass  cylinder  of  about  160  cc.  capacity. 
When  about  50  cc.  have  been  so  collected,  take  away  the  cylinder 
and  replace  it  with  a  fresh  one.  Measure  the  nitrogen  collected 
as  follows:  Dilute  the  collected  distillate  with  ammonia-free 
water  to  100  cc.  and  pour  it  into  one  of  the  cylinders  in  which 
has  been  placed  1J  cc.  of  the  Nessler  reagent. 

Prepare  a  standard  solution,  by  adding  to  a  similar  cylinder 
*  Sutton,  "  Volumetric  Anal.,"  p.  446. 


HYDROGEN  IN   STEEL  153 

\\  cc.  of  Nessler  reagent,  100  cc.  of  ammonia-free  water,  and 
1  cc.  of  the  standard  ammonia  solution.  If  the  colors  do  not 
agree,  prepare  other  standards,  varying  the  amount  of  the  am- 
monia solution  until  the  color  of  the  standard  matches  that  of 
the  solution  from  the  steel. 

When  about  100  cc.  of  distillate  has  been  collected  in  the 
second  cylinder,  replace  it  by  another.  Estimate  its  nitrogen 
content  as  before.  Continue  until  the  distillate  comes  over  free 
from  ammonia.  Then  add  together  the  number  of  cubic  cen- 
timeters of  standard  ammonium  chloride  solution  used.  Divide 
the  sum  by  3,  and  each  cubic  centimeter  having  the  value  of 
0.01  mgm.  of  N  will  be  equal  to  0.001  per  cent  of  N  in  the  steel. 

De  Osa  *  found  that  the  method  above  gave  low  results  and  that 
the  method  of  Boussingault  was  more  satisfactory,  although  it  did  not 
always  give  concordant  results.  By  this  method  the  steel  is  dissolved 
in  hydrochloric  acid  in  the  presence  of  C02,  the  NH3  is  distilled  into 
a  measured  quantity  of  very  weak  standard  sulphuric  acid  solution 
(0.01  normal)  and  the  uncombined  acid  measured  by  titrating  it  with 
a  standard  alkaline  solution,  or  by  treating  it  with  a  mixture  of  KIOi 
and  KI  and  titrating  the  iodine  liberated. 

HYDROGEN  IN  STEELf 

Outline.  The  steel  is  ignited  in  a  silica  tube  in  a  current 
of  oxygen.  Hydrogen  from  the  steel  combines  with  the  oxygen, 
and  the  water  formed  is  absorbed  in  phosphoric  anhydride  and 
weighed. 

Apparatus.  The  operation  is  carried  out  in  a  combustion 
furnace  provided  with  two  silica  tubes  (Fig.  73),  one  above  the 
other,  each  75  cms.  long.  The  lower  one,  in  which  the  steel  is 
placed,  is  2  cms.  in  diameter;  and  the  upper  one,  in  which  the 
oxygen  is  purified,  1  cm.  in  diameter.  Each  tube  has  placed 
within  it  a  15-cm.  roll  of  platinum  gauze  to  serve  as  a  catalyzer. 

*  Rev.  Metal.,  5,  493-504. 

t  "  Anal,  of  Iron  and  Steel,"  American  Rolling  Mill  Co.,  Middletown, 
Ohio,  p.  35. 


154 


METALLURGICAL  ANALYSTS 


The  oxygen  is  passed  through  the  hot  1-cm.  silica  tube  at  the 
rate  of  100  cc.  per  minute  to  oxidize  whatever  impurities  it  may 
contain.  It  then  passes  through  the  following  purifying  train: 


FIG.  73. — Apparatus  for  the  Determination  of  Hydrogen  in  Steel. 


first,  a  wash  bottle  containing  a  strong  solution  of 
potassium  hydroxide;  second,  through  a  bottle  con- 
taining sticks  of  potassium  hydroxide;  third,  through 
concentrated  sulphuric  acid;  and  finally,  through  a 
tube  containing  phosphoric  anhydride,  held  loosely 
in  glass  wool.  The  oxygen  then  enters  the  2-cm. 
silica  tube  containing  the  steel,  where  it  combines 
with  the  hydrogen  liberated  from  the  steel,  forming 
water.  It  then  passes  into  the  4-in.  U-tube  provided 
with  glass  stoppers,  and  containing  phosphoric  anhydride  (held 
loosely  in  glass  wool)  in  which  the  water  is  absorbed.  From  this 
tube  the  gas  passes  through  a  bottle  containing  concentrated 
sulphuric  acid,  which  shows  the  rate  at  which  .the  gas  flows. 

H  in  Steel.  Heat  the  silica  tubes  to  redness  and  pass  oxygen 
through  at  the  rate  of  100  cc.  per  minute.  Detach  the  U-tube, 
let  it  cool  in  the  balance  case  fifteen  minutes,  and  weigh.  Then 
connect  it  with  the  silica  tube,  through  a  one-hole  stopper,  turn 
on  the  heat,  and  the  apparatus  is  ready  for  combustion. 

Weigh  from  10  to  40  gms.  of  the  steel,  in  as  large  pieces  as 
are  available,  and  place  the  sample  in  a  boat  containing  ignited 
alundum.  Remove  the  stopper  from  the  end  of  the  silica  tube 
at  which  the  oxygen  enters,  insert  the  boat  containing  the  steel 
into  the  red-hot  tube.  Close  the  tube  and  continue  passing 
the  oxygen,  at  the  rate  of  100  cc.  per  minute,  for  thirty  minutes. 


OXYGEN  IN   STEEL 


155 


Then  disconnect  the  U-tube,  cool  it  in  the  balance  case,  and 
weigh.  The  weight  of  water,  multiplied  by  the  factor  0.1119, 
will  give  the  weight  of  hydrogen  in  the  steel. 

It  is  necessary  to  run  a  blank,  using  the  same  amount  of 
oxygen  that  is  required  for  the  test,  and  it  should  be  run  for 
the  same  length  of  time.  The  increase  in  weight  for  the  blank, 
which  is  due  to  the  oxidation  of  the  rubber  connections,  should 
not  exceed  1  mgm. 

The  temperature  at  which  the  combustion  takes  place  should 
not  be  so  high  that  the  steel  will  absorb  all  the  oxygen.  It  is 
not  necessary  to  convert  all  the  metal  to  oxide. 

OXYGEN  IN  STEEL 

LEDEBUR'S  METHOD  * 

Outline.  The  steel  is  ignited  in  a  fused .  silica  combustion 
tube  in  a  current  of  purified  hydrogen.  The  oxygen  liberated 
from  the  steel  combines  with  the  hydrogen,  and  the 
water  formed  is  absorbed  in  phosphoric  anhydride  and 
weighed. 

Apparatus.      The    combustion  furnace  (Fig.  74)  is 
the  same  as  that  described  on  page  154  in  the  Method 
for  Hydrogen  in  Steel.     The  hydrogen  is  gen- 
erated from  hydrochloric  acid  on  pure  iron  or 


FIG.  74. — Apparatus  for  the  Determination  of  Oxygen  in  Steel. 

mossy  zinc.     It   is  purified  and   dried  by  passing  it  first  over 
sticks    of    potassium    hydroxide;    second,    through    a    30    per 

*  Cushman,  Jour.  Ind.  and  Eng.  Chem.,  3,  372.     "  Meth.  for  the  Anal, 
of  Iron  and  Steel,"  American  Rolling  Mill  Co.,  Middletown,  Ohio,  41. 


156  METALLURGICAL  ANALYSIS 

cent  solution  of  potassium  hydroxide;  and  finally,  before 
entering  the  1-cm.  silica  tube,  through  concentrated  sulphuric 
acid.  From  the  small  silica  tube  the  gas  passes  through 
a  U-tube  containing  phosphoric  anhydride  (held  loosely  in 
glass  wool)  to  remove  the  water  formed  from  the  small  amount 
of  oxygen  that  comes  over  with  the  hydrogen.  From  the  U-tube 
the  hydrogen  passes  to  the  large  combustion  tube  and  com- 
bines with  the  oxygen  of  the  steel  to  form  water.  The  water 
is  absorbed  in  phosphoric  anhydride  in  a  U-tube,  and  weighed. 
A  guard  tube  containing  phosphoric  anhydride  (held  loosely  in 
glass  wool)  follows  the  U-tube  to  protect  it  from  moisture  in  the  air. 

Preparation  of  the  Sample.  The  sample  should  be  drilled  with 
the  machine  drill,  at  low  speed,  to  prevent  partial  oxidation. 
The  drillings  should  be  fine  and  should  be  free  from  all  particles 
of  oil  or  dust. 

O  in  Steel.  Weigh  accurately  25  gms.  of  the  finely  divided 
drillings  and  transfer  the  sample  to  a  nickel  or  platinum  boat. 
Place  the  boat  in  the  combustion  tube,  close  the  tube,  attach 
the  weighed  U-tube  (which  is  provided  with  glass  stoppers) 
and  the  guard  tube.  Pass  hydrogen  through  the  furnace  until 
the  air  has  all  been  swept  out  of  the  furnace  and  connections 
while  it  is  cold.  Turn  on  the  heat  and  raise  the  temperature 
quickly  to  a  bright  red  heat  (about  850°  C.)  and  hold  at  this 
temperature  while  the  hydrogen  is  passed  at-  the  rate  of  100 
cc.  per  minute,  for  thirty  minutes.  When  the  combustion  is 
complete,  turn  off  the  heat  and  cool  the  furnace,  as  rapidly  as 
possible,  to  the  ordinary  temperature.  This  may  be  done  by 
turning  on  a  blast  of  cold  air.  When  the  furnace  is  cold,  detach 
the  U-tube,  with  its  guard  tube.  With  an  aspirator  draw  air 
into  the  U-tube  through  a  drying  tube  to  replace  the  hydrogen, 
and  weigh  the  U-tube.  The  weight  of  water,  multiplied  by  the 
factor  0.8889,  will  give  the  weight  of  oxygen  in  the  steel. 

A  blank  should  be  run  occasionally  and  the  necessary  correc- 
tion made  on  all  determinations. 


ANALYSIS  OF  IKON  SLAGS  157 


ANALYSIS  OF  IRON  SLAGS 

Sampling.  If  slags  are  chilled  while  hot,  they  are  much 
more  easily  decomposed  by  acids  than  if  left  to  cool  slowly. 
Therefore  the  sample  should  be  taken  while  the  slag  is  molten 
and  poured  either  into  water  or  on  a  cold  steel  or  iron  plate. 
A  steel  rod  may  be  stirred  into  the  hot  slag,  withdrawn,  and  dipped 
into  water,  or  left  for  the  slag  to  cool  on  the  rod  in  the  air. 

Since  the  composition  of  slag  differs  from  hour  to  hour,  a 
sample  should  be  taken  each  time  the  slag  is  tapped  and  the 
accumulated  samples  for  the  day  mixed  and  crushed,  and  properly 
sampled  for  analysis.  (See  p.  8.)  The  samples  should  be  ground 
in  a  mechanical  grinder  or  on  a  bucking-board,  and  finally  in  an 
agate  mortar.  Pass  a  magnet  through  the  ground  slag,  to  take 
out  particles  of  iron  that  may  be  included  in  it.  It  is  then 
ready  for  analysis. 

Insoluble  Residue.  Weigh  0.5  gm.  of  slag  and  transfer  it  to 
a  porcelain  casserole.  Add  20  cc.  of  water  and  stir  until  the 
slag  is  suspended  in  the  water.  Add  10  cc.  of  strong  hydro- 
chloric acid,  cover,  and  heat  to  dissolve.  Add  a  few  drops  of 
nitric  acid  and  evaporate  to  dryness.  Add  to  the  residue  3  cc. 
of  strong  hydrochloric  acid  and  evaporate  again  to  dryness. 
Cool,  add  30  cc.  of  dilute  hydrochloric  acid  (1  :  1),  heat  to  dis- 
solve, and  filter.  Wash  with  hot  dilute  hydrochloric  acid  and 
hot  water.  Burn  the  filter  with  the  precipitate  in  a  platinum 
crucible,  cool  in  a  desiccator,  and  weigh  as  silicious  residue. 

SiC>2  in  Slag.  After  the  silicious  residue  is  weighed,  add  a 
few  drops  of  sulphuric  acid,  and  enough  hydrofluoric  acid  to 
dissolve  the  silica.  Evaporate  and  weigh  in  the  usual  manner. 
(See  p.  71.)  The  loss  in  weight  represents  Si02. 

Al2O3+Fe2O3  in  Slag.  Heat  the  filtrate  from  the  silicious 
residue  to  boiling  and  add  a  slight  excess  of  ammonia.  Boil 
until  the  smell  of  ammonia  is  faint.  Let  the  precipitate  settle, 
filter,  wash  with  hot  water,  burn,  and  weigh  as 


158  METALLURGICAL  ANALYSIS 

CaO  in  Slag.  Heat  the  filtrate  from  aluminic  and  ferric 
oxides  to  boiling.  Add  25  cc.  of  a  saturated  solution  of  ammo- 
nium oxalate  and  10  cc.  of  ammonia. 

CaCl2+(NH4)2C204  =  CaC204+2NH4Cl. 

Boil  a  few  minutes  and  let  the  precipitate  settle.  Filter,  and 
wash  with  hot  water. 

If  the  flux  is  dolomitic,  for  a  complete  separation  of  the  magnesia, 
dissolve  the  precipitate  of  calcium  oxalate  in  dilute  hydrochloric  acid, 
dilute,  reprecipitate,  and  filter,  as  described  above. 

This  precipitate  may  be  burned  and  weighed  as  CaO,  or,  where 
many  determinations  are  to  be  made,  it  is  better  to  measure  the  lime 
volumetrically,  as  follows: 

Remove  the  filter  paper  containing  the  precipitate  of  calcium 
oxalate  from  the  funnel,  carefully  unfold  it,  and  spread  it  out 
smoothly  against  the  inside  of  a  500-cc.  beaker,  with  the  side 
of  the  paper  containing  the  precipitate  nearest  the  bottom  of 
the  beaker.  (See  Fig.  52  on  p.  61.)  With  a  jet  of  water 
carefully  wash  the  precipitate  from  the  paper.  Withdraw 
the  paper,  add  to  the  precipitate  100  cc.  of  dilute  sulphuric  acid 
(1  :  3). 

CaC204+H2S04  =CaS04+H2C204. 

Heat  to  boiling,  and  while  hot  titrate  with  standard  potas- 
sium permanganate  solution. 

5H2C204+2KMn04+3H2S04=K2S04+2MnS04+8H20+10C02. 

By  combining  the  two  equations  above  and  comparing  it  with 
that  on  page  57  for  the  titration  of  Fe,  it  is  evident  that  the  value 
of  1  cc.  of  permanganate  solution  in  Fe,  multiplied  by  0.50205, 
will  give  its  value  in  CaO. 

5CaC204+2KMn04+8H2S04  =  5CaSO4 

-fK2S04+2MnS04.+8H20-hlOC02. 


ANALYSIS  OF  IRON   SLAGS  159 

MgO  in  Slag.  Add  hydrochloric  acid  to  the  filtrate  from  the 
calcium  oxalate  until  it  is  slightly  acid,  and  then  add  20  cc. 
of  10  per  cent  solution  of  microcosmic  salt.  Evaporate  the 
solution  to  about  250  cc.  and  cool  it.  When  cold  add  ammonia, 
drop  by  drop,  stirring,  until  the  solution  is  alkaline.  Then 
add  25  cc.  of  strong  ammonia.  Let  the  solution  stand  several 
hours,  stirring  occasionally.  Filter,  wash  with  dilute  ammonia 
(1:3),  burn,  and  weigh.  (See  magnesia  in  limestone,  p.  165.) 

FeO  in  Slag.  Weigh  5  gms.  of  the  sample  and  transfer  it  to  a 
porcelain  casserole.  Add  30  cc.  of  water  and  stir  until  the  slag  is 
in  suspension  in  the  water.  Add  30  cc.  of  dilute  hydrochloric  acid 
(1  :  1).  Cover,  and  evaporate  the  solution  to  dryness.  Cool, 
add  30  cc.  of  dilute  hydrochloric  acid  (1  :  1),  boil  to  dissolve  the 
iron,  filter,  and  wash.  Then  proceed  with  the  reduction  and 
titration  of  the  iron  by  the  potassium  dichromate  method  given 
on  page  62.  The  weight  of  iron,  multiplied  by  1.2865,  will  give 
the  corresponding  weight  of  FeO. 

A^Os  in  Slag  (by  difference).  From  the  determination  of 
Fe  above,  calculate  the  equivalent  of  the  Fe  in  Fe2Oa  by  multiply- 
ing the  weight  of  Fe  by  the  factor  1.4298.  Deduct  the  weight 
of  Fe20s  from  the  combined  weight  of  Al2O3+Fe203  as  de- 
termined by  the  method  on  page  157,  and  calculate  the  per- 
centage of  A^Oa. 

A12O3  in  Slag  (Phosphate  method).  Weigh  0.5  gm.  of  the 
slag  and  treat  it  according  to  the  method  described  above  for 
the  determination  of  insoluble  residue.  After  the  filtration  and 
washing  of  the  insoluble  residue,  proceed  with  the  determina- 
tion of  A^Oa  in  the  filtrate  according  to  the  phosphate  method 
given  on  page  87. 

S  in  Slag.  Weigh  1  gm.  of  slag,  and  transfer  it  to  a  porcelain 
casserole.  Add  5  cc.  of  bromine  water  and  50  cc.  of  aqua  regia. 
Evaporate  to  dryness,  dissolve  in  a  little  hydrochloric  acid  and 
water,  filter,  and  proceed  in  the  manner  described  for  the 
determination  of  sulphur  in  ore.  (See  p.  75.) 


160  METALLURGICAL  ANALYSIS 

Mn  in  Slag.  Weigh  1  gm.  of  slag  and  proceed  according 
to  the  colorimetric  method  for  manganese  in  ore  (p.  92);  or, 
if  the  slag  is  high  in  manganese,  the  bismuthate  method  or  Julian's 
method  may  be  used. 

ANALYSIS  OF  LIMESTONE 

Sampling.  Limestone  is  sampled  in  a  similar  manner  to 
that  employed  in  the  sampling  of  iron-ore  (see  p.  45),  but 
usually  so  large  a  sample  is  not  required,  since  it  is  a  more 
uniform  and  less  valuable  material.  The  sample  is  crushed, 
mixed,  divided,  and  ground  to  a  fine  powder  for  analysis  in  the 
usual  manner. 

Reagents.    Sodium  carbonate.    Dry  Na2C03. 

Dilute  hydrochloric  acid  (1  :  1). 

Oxalic  acid.  Dissolve  40  gms.  (H2C2O4H-2H2O  in  1  liter  of 
water. 

Sodium  phosphate.  Dissolve  100  gms.  HNa2PO4+12H20  in 
1  liter  of  water. 

INSOLUBLE   SILICIOUS  MATTER  IN  LIMESTONE 

Weigh  1  gm.  of  the  powdered  limestone  and  transfer  it  to  a 
small  beaker.  Add  30  cc.  of  dilute  hydrochloric  acid  and  1  cc. 
of  nitric  acid.  Cover  the  beaker  and  heat  it  to  dissolve  as  much 
as  possible  of  the  sample.  Evaporate  the  solution  to  dryness 
and  heat  the  residue  in  an  air-bath  one  hour  at  120°  C.  Cool, 
add  10  cc.  of  strong  hydrochloric  acid,  warm  gently  and  add 
50  CO;  of  hot  water.  Filter,  wash  the  residue  with  hot  dilute 
hydrochloric  acid,  and  then  wash  with  hot  water.  Burn  the 
filter  and  contents  in  a  platinum  crucible,  cool  in  a  desiccator 
and  weigh. 


SILICA  IN  LIMESTONE  161 


SILICA  IN  LIMESTONE 

After  weighing  the  insoluble  silicious  matter  (see  above), 
add  to,  the  crucible  about  0.5  gm.  sodium  carbonate  and  fuse. 
Cool  and  dissolve  the  fusion  in  a  casserole  with  dilute  hydro- 
chloric acid.  Carefully  wash  off  the  crucible  and  cover,  letting 
the  washings  run  into  the  casserole.  Evaporate  the  solution  to 
dryness  and  heat  the  residue  in  an  air-bath  one  hour  at  120°  C. 
Cool,  add  10  cc.  of  hydrochloric  acid,  warm  and  add  50  cc.  of 
hot  water.  Filter,  wash  with  dilute  hydrochloric  acid  and  then 
wash  with  hot  water.  Burn,  cool  in  a  desiccator,  and  weigh  the 
Si02. 

In  carrying  out  this  process  about  1  per  cent  of  the  silica  dissolves 
and  passes  through  with  the  filtrate.  For  exact  work,  the  filtrate 
should  be  taken  to  dryness  again,  dissolved,  and  filtered  through  a  fresh 
paper,  and  the  two  papers  burned  together.  If  this  treatment  is  adopted, 
the  first  heating  of  the  residue  need  not  be  so  prolonged.  It  is  sufficient 
to  evaporate  the  solution  to  dryness,  take  up  the  residue  in  dilute  acid 
and  filter. 

OXIDES  OF  IRON,  ALUMINUM,  ETC.,  IN  LIMESTONE 

Combine  the  filtrates  from  the  insoluble  silicious  matter 
and  the  silica,  heat  the  solution  to  boiling  and  add  a  slight  excess 
of  ammonia.  Boil  until  the  odor  of  ammonia  is  faint. 

Aluminum  hydroxide  is  slightly  soluble  in  ammonia,  but  this  effect 
is  largely  neutralized  by  the  presence  of  ammonium  chloride. 

Let  the  precipitate  settle  a  few  minutes,  filter,  and  wash 
quickly  with  hot  water. 

The  solution  absorbs  C02  from  the  air,  which  precipitates 
calcium  as  CaCOs.  If  accurate  results  are  required,  wash 
the  precipitate  into  a  beaker,  add  hydrochloric  acid,  and  heat 
to  dissolve;  dilute  with  hot  water,  add  a  slight  excess  of  ammonia, 
boil  until  the  odor  is  faint,  let  the  precipitate  settle,  and  filter  and 
wash  in  the  manner  described  above, 


162  METALLURGICAL  ANALYSIS 

Burn  the  filter  and  contents  in  a  platinum  crucible.  Cool 
in  a  desiccator  and  weigh. 

The  oxides  weighed  are  chiefly  those  of  iron  and  aluminum,  but 
if  the  limestone  contains  titanium,  phosphorus,  vanadium,  chromium, 
and  zirconium,  their  oxides  also  will  be  present.  For  the  separate 
determination  of  these  elements  in  limestone,  see  the  index  for  the 
methods  for  their  determination  in  ores. 

LIME    IN    LIMESTONE 
GRAVIMETRIC  METHOD 

Combine  the  filtrates  from  the  hydroxides  of  iron,  aluminum, 
etc. 

The  total  volume  should  measure  about  250  cc.  and  there 
should  be  enough  ammonium  chloride  present  to  prevent  the  pre- 
cipitation of  magnesia  when  the  solution  is  near  the  neutral  point. 

Add  1  drop  of  methyl  orange,  heat  to  boiling,  and  add  oxalic 
acid  until  the  solution  is  acid.  While  boiling,  stir,  and  add 
ammonia  slowly  until  the  solution  is  slightly  alkaline.  After 
the  addition  of  the  ammonia,  boil  and  stir  a  few  minutes.  Let 
the  precipitate  settle. 

CaCl2+H2C204+2NH4OH=CaC204+2NH4Cl+2H20. 

Decant  the  clear  solution  through  a  filter,  wash  once  by 
decantation  with  hot  water,  leaving  the  precipitate  in  the  beaker. 
To  free  this  precipitate  of  magnesium  oxalate  which  comes 
down  with  it,  dissolve  it  in  10  cc.  of  dilute  hydrochloric  acid, 
add  about  100  cc.  of  hot  water,  boil,  and  reprecipitate  the  cal- 
cium oxalate  with  oxalic  acid  and  ammonia.  Filter  on  the  same 
filter  paper  used  for  the  decantation,  and  wash  thoroughly 
with  hot  water.  Reserve  both  filtrates  for  magnesia. 

Place  the  filter  and  precipitate  in  a  platinum  crucible.  Care- 
fully dry,  and  burn  off  the  paper  with  a  Bunsen  burner.  Finally 
heat  with  a  blast  lamp  to  drive  off  all  the  CO  and  CO2. 

4  =  CaO+C02+CO. 


LIME  IN  LIMESTONE  163 

Cool  in  a  desiccator  and  weigh  quickly. 

CaO  readily  absorbs  moisture  from  the  atmosphere.  Repeat 
the  burning  and  weighing  until  the  weight  is  constant. 

The  weight  of  CaO  multiplied  by  100  represents  the  percent- 
age of  CaO,  or  lime,  in  the  limestone.  This  percentage  of  CaO, 
multiplied  by  the  factor  1.7847,  will  give  the  percentage  of 
CaC03. 

Burning  large  precipitates  of  calcium  oxalate  completely  to  CaO 
and  weighing  adds  considerably  to  the  time  of  making  the  analysis. 
If  many  determinations  of  lime  are  to  be  made,  the  following  volumetric 
method  is  recommended. 

LIME  IN  LIMESTONE 

VOLUMETRIC  METHOD 

After  the  calcium  oxalate  has  been  transferred  to  the  filter 
(see  the  preceding  method),  wash  it  with  hot  water  until  the 
wash  water  comes  through  free  from  oxalates. 

Test  by  collecting  a  few  cubic  centimeters  in  a  small  beaker,  acidi- 
fying with  H2S04,  heating  nearly  to  boiling,  and  adding  a  drop  of  KMn04 
solution.  If  the  color  of  the  permanganate  fades,  oxalate  is  still  present. 

When  thoroughly  washed,  transfer  the  precipitate  from 
the  paper  to  a  beaker,  with  hot  water.  (See  p.  61  for  the  method 
of  transfer.)  Then  wash  off  the  paper  with  a  little  dilute  H?SO4 
(1:5)  from  a  wash  bottle,  and  finally,  with  hot  water.  Remove 
the  paper.  Add  a  few  cubic  centimeters  of  sulphuric  acid  to 
dissolve  the  precipitate. 

(1)  CaC204+H2S04  =  CaS04+H2C204. 

Dilute  with  hot  water  and,  while  hot  (70°  C.),  titrate  with 
standard  potassium  permanganate  solution. 

(2)  5H2C204+2KMn04+3H2S04  =K2S04+2MnS04+8H20+10C02. 

The  standard  permanganate  solution  used  for  the  titration 
of  iron  may  be  used  for  lime.  Its  value  in  iron,  multiplied  by 


164  METALLURGICAL  ANALYSIS 

0.50206,  will  give  the  value  per  cubic  centimeter ,  in  CaO,  or, 
multiplied  by  0.89604,  will  give  the  value  in  CaC03.  These 
factors  are  calculated  from  the  above  reactions  and  the  reaction 
of  KMnCU  with  iron  (p.  57).  Two  molecules  of  KMnCU  react 
with  10  atoms  of  Fe  in  the  one  case  (p.  57)  and  with  5  molecules 
of  oxalic  acid  in  the  other  (equation  2  above)  which  are  equivalent 
to  5  atoms  of  Ca  (equation  1  above).  From  the  weight  of  Ca 
the  corresponding  weights  of  CaO  and  CaCOs  are  at  once  deduced. 
The  more  accurate  and  desirable  method,  however,  is  to 
standardize  the  solution  against  a  weighed  quantity  of  pure 
Iceland  spar,  which  has  been  treated  by  this  method. 

TITRATION  OF  BOTH  CALCIUM  AND  MAGNESIUM 

A  method  for  the  titration  of  both  calcium  and  magnesium 
in  the  same  solution  has  been  devised  by  P.  J.  Fox,*  by  which 
the  calcium  is  precipitated  as  oxalate,  and  the  magnesium  as 
magnesium  ammonium  arsenate  (MgNH^AsCU),  by  the  addi- 
tion of  ammonium  arsenate.  The  precipitates  are  filtered  to- 
gether from  the  solution,  and  transferred  to  a  flask.  Sulphuric 
acid  is  added,  and  the  calcium  is  measured  by  titrating  the  lib- 
erated oxalic  acid,  after  it  is  heated,  with  KMnCU  solution. 
The  solution  is  cooled,  KI  added,  and  the  liberated  iodine 
titrated  with  standard  sodium  tfyiosulphate  solution,  without 
the  addition  of  starch. 

As205+4HI  =As203+2H20+2I2. 

The  flask  should  be  screened  from  the  light  with  black  paper 
during  the  titration  to  prevent  the  liberation  of  iodine  by  the 
action  of  light. 

*  Jour.  Ind.  and  Eng.  Chem.,  5,  910  (1913). 


MAGNESIA  IN  LIMESTONE  165 


MAGNESIA  IN  LIMESTONE 

Combine  in  one  solution  .  the  filtrates  from  the  calcium 
oxalate  and  acidify  it  with  hydrochloric  acid.  Add  20  cc. 
of  sodium  phosphate  solution  (100  gms.  HNa2PO4  +  12H2O 
per  liter).  Evaporate  the  solution  until  a  precipitate  begins 
to  form.  Add  hot  water  until  the  precipitate  dissolves.  Add 
ammonia,  drop  by  drop,  stirring,  until  the  solution  is  alkaline. 
Then  add  a  volume  of  ammonia  (sp.gr.  0.90)  equal  to  about 
one-fourth  the  volume  of  the  solution.  Stir  well  and  let  the 
precipitate  settle  several  hours. 

A  mechanical  stirrer  is  recommended.  Where  the  stirring  rod 
touches  the  sides  of  the  beaker,  the  precipitate  adheres  and  is  removed 
with  great  difficulty.  If  the  stirring  is  continuous,  precipitation  should 
be  complete  in  half  an  hour. 

MgCl24-NH40H+HNa2P04=MgNH4P04+2NaCl+H20. 

Filter,  and  if  the  precipitate  of  magnesium  ammonium 
phosphate  is  large,  or  if  other  salts  have  crystallized  with  it, 
dissolve  the  precipitate  in  a  little  hydrochloric  acid,  dilute  the 
solution  with  water,  add  5  cc.  of  sodium  phosphate  solution 
and  ammonia,  in  the  manner  described  above.  Stir,  let  the 
precipitate  settle,  and  filter.  Wash  with  water  containing  100 
cc.  NH4OH  (sp.gr.  0.90)  and  1  cc.  HNO3  per  liter. 

Dry  the  precipitate;  separate  it  from  the  paper.  (See  Fig. 
31,  p.  27.)  Burn  the  paper  in  a  porcelain  crucible.  When  the 
carbon  is  all  burnt,  add  the  precipitate  and  heat  at  a  red  heat 
with  a  Bunsen  burner  until  the  precipitate  is  white.  Then  heat 
at  a  high  temperature  with  the  blast  lamp  a  few  minutes.  Cool 
in  a  desiccator  and  weigh 


2NH4MgP04  =  Mg2P207+2NH3+H20. 

The  factor  for  MgO  in  Mg2P207  is  0.36207;  and  for  MgCO3 
is  0.75718. 


166 


METALLURGICAL  ANALYSIS 


If  the  filter  paper  is  burned  in  contact  with  the  phosphate  pre- 
cipitate, there  is  danger  that  phosphorus  will  be  reduced  and  the  deter- 
mination spoiled.  If  this  takes  place  in  a  platinum  crucible,  the  phos- 
phorus combines  with  the  platinum,  making  it  brittle  and  causing  cracks 
to  form. 

PHOSPHORUS  AND  SULPHUR  IN  LIMESTONE 

For  methods  for  the  determination  of  phosphorus,  sulphur, 
and  other  elements  in  limestone  see  the  methods  for  these  ele- 
ments in  iron  ore. 

CARBON  DIOXIDE  IN  LIMESTONE 

Apparatus  and  Reagents.     The  limestone  is  dissolved  in  a 

flask  (Fig.  75  C),  in  dilute  HC1. 

CaC03+2HCl  =CaCl2+H20+C02. 


FIG.  75. — Apparatus  for  the  Determination  of  Carbon 
Dioxide  in  Limestone. 


The  liberated  C02,  after  purification,  is  absorbed  in  a  KOH 
bulb  and  weighed. 

A  is  a  U-tube  containing  soda  lime — a  mixture  of  calcium 
and  sodium  hydroxides — which  removes  CO2  from  the  air  drawn 
into  the  apparatus. 

B.  A  separatory  funnel  in  which  is  placed  150  cc.  of  dilute 
HC1  (1  :  5). 

C.  A  Florence  flask  in  which  the  sample  is  placed  for  solution. 

D.  A  bulb  tube  to  serve  as  condenser- 


CARBON  DIOXIDE  IN  LIMESTONE  167 

E.  A  U-tube  containing  a  solution  of  silver  sulphate  in  sul- 
phuric acid  to  absorb  hydrochloric  acid.     Sulphuric  acid  pre- 
vents evaporation  of  the  silver  sulphate  solution. 

F.  A  U-tube  containing  dried  but  not  fused  CaCk  which 
removes  moisture  from  the  gas.     Calcium  chloride  sometimes 
contains   impurities   which   absorb   C02,   therefore,    before   use, 
C02  should  be  passed  through  this  tube  to  saturate  the  reagent, 
and  then  a  current  of  air  should  be  passed  through  half  an  hour 
to  remove  the  excess  of  C02. 

G.  A  Geissler  bulb  with  each  of  the  small  bulbs  two-thirds 
filled  with  a  KOH  solution   (1.27  sp.   gr.)   for  the  absorption 
of  C02.     The  solution  must  be  concentrated  to  insure  the  absorp- 
tion of  CO2  and  to  prevent  evaporation. 

H.  A  tube  containing  calcium  chloride  to  absorb  moisture 
that  may  be  carried  from  the  bulb  G.  (See  Carbon  in  Steel, 
p.  117.) 

/.  A  second  calcium  chloride  tube  added  to  protect  H  from 
moisture  from  the  air. 

/.  An  aspirator  bottle  by  which  air  is  drawn  through  the 
apparatus. 

When  the  apparatus  is  set  up,  test  for  leaks  in  the  manner 
described  on  page  119. 

CO2  in  Limestone.  Connect  the  aspirator  bottle  J  and 
draw  air  through  the  apparatus  until  it  is  filled  with  air  free 
from  carbon  dioxide.  Weigh  G  and  H  and  attach  them  as 
shown  in  the  figure,  but  do  not  connect  the  aspirator  bottle  J. 
Weigh  1  gm.  of  the  finely  ground  limestone  and  transfer  it 
to  the  flask  C.  Open  the  tap  of  B  and  let  the  acid  drop  into 
the  flask  C  until  the  gas  passes  through  the  bulb  G  at  the  rate 
of  two  bubbles  per  second.  When  the  passage  of  the  gas  falls 
below  that  rate,  add  more  acid.  Finally,  when  the  addition 
of  more  acid  does  not  increase  the  action,  attach  the  aspirator 
to  /,  and  begin  the  aspiration  very  gently,  and  open  the  screw 
clamp  a.  Then  warm  the  flask  C  very  gradually  with  a  Bunsen 


168  METALLURGICAL  ANALYSIS 

burner  and  boil  gently  half  an  hour.  Detach  G  and  H,  place 
them  in  the  balance  case,  and  after  they  have  stood  fifteen 
minutes,  weigh  them.  The  same  precautions  must  be  taken  in 
weighing  that  are  pointed  out  on  page  119.  The  increase  in 
weight  represents  the  CO2  in  the  sample. 

METHODS   OF  ANALYSIS   IN    THE   METALLURGY   OF 
COPPER  AND  LEAD 

COPPER  IN  ORE 

POTASSIUM  CYANIDE  METHOD 

Outline.  The  copper  is  dissolved  from  the  ore  with  nitric 
and  hydrochloric  acids,  sulphuric  acid  is  added  and  the  solution 
is  evaporated  nearly  to  dryness.  A  little  water  is  added  and 
the  copper  is  precipitated  on  metallic  zinc  or  aluminum.  The 
copper  is  separated  from  the  solution,  washed,  and  dissolved  in 
nitric  acid.  An  excess  of  ammonia  is  added  and  the  cupram- 
monium  nitrate  is  titrated  with  standard  potassium  cyanide 
solution.  * 

Reagents.    Dilute  nitric  acid  (1  :  4). 

Bromine  water;   cold  water  saturated  with  Br. 

Sheet  zinc  or  aluminum. 

Standard  solution  of  potassium  cyanide.  Dissolve  21  gms. 
of  KCN  in  water  and  dilute  the  solution  to  1  liter.  Standardize 
the  solution  as  follows:  Weigh  accurately  about  0.2  gm.  of  pure 
copper  foil  and  transfer  it  to  a  250-cc.  Erlenmeyer  flask.  Add 
5  cc.  of  strong  nitric  acid.  When  in  solution,  dilute  with  25 
cc.  of  water  and  add  5  cc.  of  bromine  water.  Boil  out  the 
bromine,  and  add  50  cc.  of  cold  water  and  10  cc.  of  ammonia. 
Cool  to  the  temperature  of  the  room,  dilute  to  150  cc.,  and  titrate 
with  the  potassium  cyanide  solution. 

The  cyanide  solution  does  not  hold  its  strength  well.  It 
*  For  the  method  of  sampling  see  p.  8. 


COPPER  IN  ORE  169 

should,  therefore,  be  standardized  frequently,  the  titration  of 
the  standard  should  be  done  at  the  same  time  that  the  ores  are 
titrated,  and  all  brought  to  the  same  tint  for  an  end-point. 
When  the  blue  color  begins  to  fade,  proceed  more  slowly  with  the 
titration,  and  after  each  addition  of  solution  allow  a  little  time 
for  the  reaction  to  take  place  before  further  additions  are  made. 
As  the  end-point  is  approached,  the  solution  changes  from  pale 
blue  to  violet,  and  finally  to  faint  pink.  On  standing,  the  color 
fades;  therefore,  all  titrations  should  be  made  in  about  the  same 
time. 

Cu  in  Ore.  Weigh  1  gm.  of  ore  (0.5  gm.  if  the  ore  contains 
more  than  40  per  cent  copper)  and  transfer  it  to  a  250-cc. 
Erlenmeyer  flask.  Add  10  cc.  of  nitric  acid,  and  boil  gently  to 
decompose  the  ore.  If  decomposition 
is  not  complete,  add  5  cc.  of  hydro- 
chloric acid  and  boil.  Add  7  cc.  of 
sulphuric  acid  and  boil  until  dense 
sulphuric  acid  fumes  are  evolved. 


This  operation  is  carried  on  best  by 
holding  the  flask  by  the  neck  with  a  test- 
tube  holder  and  shaking  it  over  the  open 
Bunsen  flame  under  a  hood.  (Fig.  76.) 
It  should  be  boiled  almost  to  dryness  to  FIG.  76. — Flask  for  Copper 
insure  the  expulsion  of  all  nitric  acid.  Determinations. 

Cool,  and  add  20  cc.  of  cold  water.  If  the  ore  contains 
silver,  add  1  drop  of  hydrochloric  acid  to  precipitate  the  silver. 
Shake  the  flask,  let  it  stand  hot  until  the  ferric  sulphate  dis- 
solves, filter  the  solution  into  a  small  flask,  and  wash  the  residue 
with  hot  water,  keeping  the  volume  down  to  about  60  cc.  Put 
into  the  flask  three  pieces  of  sheet  aluminum,  about  15  mm. 
X40  mm.,  with  the  ends  bent  to  prevent  the  sheets  from  lying 
flat  on  the  bottom  of  the  flask.  Boil  the  solution  to  precipitate 
the  copper.  The  copper  is  not  precipitated  in  a  weakly  acid 
solution,  but  is  rapidly  precipitated  after  boiling  the  solution 


170  METALLURGICAL  ANALYSIS 

down  to  the  proper  concentration.  When  the  copper  is  com- 
pletely precipitated, .  decant  the  solution  through  a  filter  and 
wash  the  copper  and  aluminum  by  decantation  two  or  three 
times. 

A  weak  solution  of  hydrogen  sulphide  may  be  used  as  a  wash  to 
prevent  the  oxidation  and  solution  of  the  finely  divided  copper. 

Place  the  flask  under  the  funnel,  pour  through  the  filter  10  cc. 
of  warm  dilute  nitric  acid  (1  :  4).  Replace  the  flask  with  a 
beaker.  Shake  the  flask  and  warm  it  slightly  to  dissolve  the 
copper.  Empty  the  flask  into  the  beaker  and  pour  the  solution 
back  into  the  flask,  leaving  the  strips  of  aluminum  in  the  beaker. 
Wash  the  aluminum  well  with  water  and  add  the  washings  to 
the  solution  in  the  flask.  Place  the  flask  under  the  funnel, 
pour  5  cc.  of  cold  bromine  water  through  the  filter  to  oxidize 
arsenic  and  antimony,  and  then  wash  the  filter  with  a  little 
hot  water.  Boil  the  solution  to  expel  the  bromine,  cool,  and 
add  10  cc.  of  ammonia.  Dilute  the  solution  to  150  cc.  and 
titrate  with  standard  potassium  cyanide  solution. 

This  method  is  not  accurate  unless  the  titrations  of  ore-solutions  are 
carried  out  under  exactly  the  same  conditions  as  exist  when  the  potas- 
sium cyanide  solution  is  standardized;  therefore,  the  volume  of  solu- 
tion, the  excess  of  ammonia,  the  temperature,  and  the  time  required 
for  titration  should  always  be  as  nearly  the  same  as  possible. 

Sheet  zinc  may  be  used  instead  of  aluminum  for  the  precipitation 
of  the  copper.  In  this  case,  after  the  copper  is  precipitated,  add  20  cc. 
of  dilute  sulphuric  acid  (1  :  1)  to  hasten  the  solution  of  the  zinc.  When 
the  zinc  is  dissolved,  fill  the  flask  to  the  neck  with  cold  water,  let  the 
copper  settle,  decant  the  clear  solution,  and  fill  and  decant  a  second 
and  a  third  time. 

Add  5  cc.  of  nitric  acid  to  the  copper  in  the  flask  and  boil  to  expel 
red  fumes.  Add  50  cc.  of  water  and  10  cc.  of  ammonia.  Cool,  dilute 
to  150  cc.,  and  titrate  with  standard  potassium  cyanide  solution. 


COPPER  IN  ORE  171 

COPPER  IN  ORE 

POTASSIUM  IODIDE  METHOD 

Outline.  The  copper  is  dissolved  from  the  ore  with  nitric 
and  hydrochloric  acids,  sulphuric  acid  is  added  and  the  solution 
evaporated  nearly  to  dryness.  A  little  water  is  added  and  the  cop- 
per is  precipitated  on  metallic  aluminum.  The  copper  is  separated 
from  the  solution,  dissolved  in  nitric  acid,  the  excess  of  acid 
neutralized  with  ammonia!  Acetic  acid  and  potassium  iodide  are 
added,  and  the  iodine  liberated  is  titrated  with  a  standard  solu- 
tion of  sodium  thiosulphate,  which  measures  the  quantity  of 
copper  indirectly. 

Reagents.     Acetic  acid  (C2H4O2;  sp.gr.  1.04). 

Starch  solution.     (See  p.  111.) 

Potassium  iodide,  KI. 

Standard  solution  of  sodium  thiosulphate.  Dissolve  19  gms. 
Na2S20s  in  water  and  dilute  the  solution  to  1  liter.  To  stand- 
ardize this  solution,  dissolve  about  0.2  gm.  of  pure  copper  foil 
in  5  cc.  of  strong  nitric  acid;  dilute  the  solution  with  25  cc. 
of  water,  and  add  5  cc.  of  bromine  water.  Boil  off  the  excess 
of  bromine,  remove  from  the  heat,  and  add  a  slight  excess  of 
ammonia.  Boil  off  the  excess  of  ammonia,  and  acidify  with 
acetic  acid. 

Too  great  a  concentration  of  ammonium  salts  interferes  with  the 
reaction  between  the  copper  and  acetic  acid. 

Boil  until  any  precipitate  present  is  dissolved,  cool,  add  3 
gms.  of  potassium  iodide,  and  titrate  at  once  with  sodium  thiosul- 
phate solution  to  a  faint  brown  color.  Add  a  few  drops  of 
starch  solution  and  continue  the  titration  until  the  blue  color 
disappears. 

2Cu(C2H302)2+4KI=Cu2I2+4KC2H302-fI2. 
I2+2Na2S203  =2NaI+Na,S40.. 


172  .  METALLURGICAL  ANALYSIS 

Cu  in  Ore.  Weigh  1  gm.  of  ore  (0.5  gm.  if  the  ore  contains 
more  than  40  per  cent  copper)  and  transfer  it  to  a  250-cc. 
Erlenmeyer  flask.  Add  10  cc.  of  nitric  acid,  and  boil  gently  to 
decompose  the  ore.  If  decomposition  is  not  complete,  add  5 
cc.  of  hydrochloric  acid  and  boil.  Add  7  cc.  of  sulphuric  acid 
and  boil  until  dense  sulphuric  acid  fumes  are  evolved.  (See 
the  preceding  method  for  notes.) 

Cool,  and  add  20  cc.  of  cold  water.  If  the  ore  contains 
silver,  add  1  drop  of  hydrochloric  acid  to  precipitate  the  silver. 
Shake  the  flask,  let  it  stand  hot  until  the  ferric  sulphate  dis- 
solves, filter  the  solution  into  a  small  flask,  and  wash  the  residue 
with  hot  water,  keeping  the  volume  down  to  about  60  cc.  Put 
into  the  flask  three  pieces  of  sheet  aluminum,  about  15  mm. 
X40  mm.,  with  the  ends  bent  to  prevent  the  sheets  from  lying 
flat  on  the  bottom  of  the  flask.  Boil  the  solution  to  precipitate 
the  copper.  The  copper  is  not  precipitated  in  a  weakly  acid 
solution,  but  is  rapidly  precipitated  after  boiling  the  solution 
down  to  the  proper  concentration.  When  the  copper  is  com- 
pletely precipitated,  decant  the  solution  through  a  filter  and 
wash  the  copper  and  aluminum  by  decantation  two  or  three 
times. 

Place  the  flask  under  the  funnel,  pour  through  the  filter 
10  cc.  of  warm  dilute  nitric  acid  (1  :  4).  Replace  the  flask 
with  a  beaker.  Shake  the  flask  and  warm  it  slightly  to  dis- 
solve the  copper.  Empty  the  flask  into  the  beaker  and  pour 
the  solution  back  into  the  flask,  leaving  the  strips  of  aluminum 
in  the  beaker.  Wash  the  aluminum  well  with  water  and  add 
the  washings  to  the  solution  in  the  flask.  Place  the  flask  under 
the  funnel,  pour  5  cc.  of  cold  bromine  water  through  the  filter 
to  oxidize  arsenic  and  antimony,  and  then  wash  the  filter  with 
a  little  hot  water.  Boil  the  solution  to  expel  the  bromine, 
cool,  and  add  a  slight  excess  of  ammonia.  Boil  off  the  ammonia, 
acidify  the  solution  with  acetic  acid,  and  boil  until  any  pre- 
cipitate present  is  dissolved.  Cool,  add  3  gms.  of  potassium 


COPPER  IN  ORE 


173 


iodide,  and  titrate  with  standard  sodium  thiosulphate  solution 
to  a  faint  brown  color.  Add  a  few  drops  of  starch  solution, 
and  continue  the  titration  until  the  blue  color  changes  suddenly 
to  white  or  light  cream  color. 

COPPER  IN  ORE 

ELECTROLYTIC  METHOD* 

Outline.  The  ore  is  dissolved  in  acids,  and  after  adding 
sulphuric  acid  the  solution  is  boiled  nearly  to  dryness.  A 
little  nitric  acid  is  added,  the  solution  diluted  and  the  copper 
precipitated  by  electrolysis. 

Cu  in  Ore.     Weigh  the  ore  and  dissolve  it  according  to  the 
method  described  for  the  potassium  cyanide  assay  of  copper. 
After  boiling  until  dense  sulphuric  acid  fumes  are  evolved,  cool, 
add  20  cc.  of  cold  water,  and  warm  the  solu- 
tion to   dissolve  the  soluble   sulphates.     Add 
1   drop   of   hydrochloric   acid   to    precipitate 
silver.    Filter  the  solution  into  a  No.  4  beaker, 
add  2  cc.  of  nitric  acid  and  electrolyze. 

2CuS04+2H20+electric  current 
=2H2S04+Cu2+02. 

The  electrodes  are  of  platinum.  The  most 
satisfactory  cathode  is  made  of  platinum  gauze  in 
cylindrical  form,  with  platinum  wire  attached,  by 
which  it  is  connected  to  the  negative  pole  of  an 
electric  circuit.  The  anode  may  be  a  coiled  plati- 
num wire,  about  16  gauge.  (Fig.  77.) 

Before  use  the    electrodes    should  be    cleaned 
with  nitric  acid  and  washed  with  water,  and  the    FIG.  77. — Platinum 
cathode  must  be  dried  and  weighed.  Electrodes. 

The  electrodes  should  be  held  firmly  by  a  sup- 
port so  that  they  do  not  touch,  and  the  solution  should  be  diluted  to 
cover  the  cathode. 

*  Stoddard,  Jour.  Amer.  Chem.  Soc.,  31,  385.  Price  and  Meade,  "  Tech. 
Anal,  of  Brass,"  71.  Smith,  "Electro-analysis,"  63, 


174  METALLURGICAL  ANALYSIS 

The  solution  may  be  eleotrolyzed  in  a  platinum  dish.  The  dish  is 
connected  by  a  wire  to  the  negative  pole  and  serves  as  the  cathode. 
A  platinum  crucible  cover  partly  submerged  in  the  solution  and  connected 
by  a  wire  with  the  positive  pole  serves  as  anode. 

The  current  should  have  a  density  per  hundred  square 
centimeters  of  cathode  surface  (D/100)  of  0.5  ampere  at  2.5 
volts,  and  twelve  hours  should  be  a  sufficient  time  for  the  com- 
plete precipitation  of  the  copper. 

The  ordinary  110- volt  current  may  be  conveniently  and  economi- 
cally reduced  for  this  purpose  by  the  use  of  a  motor-generator  set. 
The  motor  which  drives  the  generator  takes  the  current  at  110  volts; 
the  current  from  the  generator  is  regulated  by  an  easily  variable  resist- 
ance which  controls  the  current  in  its  field.  For  the  proper  regulation 
of  the  current  a  voltmeter  and  an  ammeter  are  connected  with  the 
generator  circuit. 

Ordinary  electric  batteries  may  be  used  for  this  purpose.  Two 
or  three  gravity  cells  in  good  working  order  supply  a  satisfactory  cur- 
rent for  one  set  of  electrodes  of  the  usual  size. 

When  the  current  passes  through  the  electrolyte,  oxygen  is  set 
free  at  the  anode  and  the  copper  should  be  deposited 
on  the  cathode  in  a  smooth,  bright  copper-colored 
plate.  If  the  copper  is  dull  in  color  or  granular  in 
appearance,  it  is  easily  washed  off  and  is  also  readily 
oxidized  when  dried  in  the  air. 

When  the  solution  has  lost  its  blue  color,  test  it 
to  determine  if  all  the  copper  has  been  precipitated, 
by  taking  out  1  cc.  of  the  solution  and  adding  to  it  a 
little  strong  solution  of  hydrogen  sulphide. 

If  copper  is  still  present,  continue  the  electrolysis 
until  the  solution  gives  no  reaction  for  copper. 

If  the   resistance  of   the   solution  is  high  and  the 
^          deposition  of  the  copper  is  too  slow,  add  a  little  am- 
•^          monia  to  reduce  the  resistance. 
FIG.  78. — Anode          The  time  of  deposition  may  be  very  much  shortened 
Suitable    for     by  increasing  the  current  to  6-8  amperes  and  3-4  volts; 
Rotating.  but  under  these  conditions  the  copper  will  be  deposited 

in  a  granular  condition,  or  some  of  it  may  be 
deposited  as  copper  sulphide,  unless  the  anode  or  the  cathode  or  the 
solution  be  rotated  at  a  high  speed.  With  this  provision  the  copper 


LEAD  IN  ORE  175 

will  be  deposited  as  a  smooth  adherent  plate  even  with  a  current  strong 
enough  to  completely  precipitate  it  in  half  an  hour.  Fig.  78  shows  a 
suitable  form  of  anode  for  rotating.  It  may  be  attached  directly  to 
the  shaft  of  a  small  motor  or  to  a  belt-driven  pulley. 

When  deposition  is  complete,  withdraw  the  electrodes  from 
the  beaker  before  breaking  the  current,  at  the  same  time  wash- 
ing them  off  with  distilled  water  to  prevent  re-solution  of  the 
copper.  Disconnect  the  cathode  from  the  circuit,  wet  it  with 
a  little  alcohol,  dry,  and  weigh  it.  From  the  combined  weight 
of  the  cathode  and  copper  must  be  deducted  the  weight  of 
the  cathode. 

If  the  copper  plate  is  smooth  with  a  fine  metallic  luster,  it  may  be 
dried  by  burning  off  the  alcohol,  without  danger  of  oxidizing  the  copper. 
After  the  copper  has  been  weighed,  it  is  dissolved  from  the  cathode 
in  a  little  warm  nitric  acid. 

LEAD  IN  ORE 

MOLYBDATE    METHOD 

Outline.  The  ore  is  treated  with  hydrochloric,  nitric,  and 
sulphuric  acids  and  the  solution  evaporated  until  the  sulphuric 
acid  fumes;  water  is  added  to  take  up  soluble  sulphates.  The 
lead  sulphate  with  other  insoluble  matter  is  filtered  from  the 
solution;  the  lead  sulphate  is  dissolved  in  ammonium  acetate 
and  the  lead  measured  by  titrating  it  with  a  standard  solution 
of  ammonium  molybdate. 

Reagents.     Sulphuric  acid,  dilute  (1  :  1). 

Sulphuric  acid,  dilute  (1  :  10). 

Ammonium  acetate;  saturated  solution  of  NILiCoHsC^  in 
water. 

Solution  of  tannin.  Dissolve  1  gm.  of  CnHioOg  in  200  cc. 
of  water. 

Standard  solution  of  ammonium  molybdate.  Dissolve  4.3 
gms.  (NH4)6Mo7024+4H20  in  300  cc.  of  water,  add  a  few 


176  METALLURGICAL  ANALYSIS 

drops  of  ammonia,  and  dilute  to  1  liter.  One  cubic  centimeter 
is  equivalent  to  about  0.005  gm.  of  lead.  To  standardize  this 
solution,  weigh  0.2  gm.  of  pure  lead  foil.  Dissolve  it  in  dilute 
nitric  acid,  add  ammonia  until  the  solution  is  alkaline,  boil, 
acidify  the  solution  with  acetic  acid,  and  titrate  with  the  am- 
monium molybdate  solution,  using  tannin  solution  on  a  porcelain 
plate  as  indicator. 

Run  a  blank,  by  titrating  the  same  volume  of  solution  con- 
taining all  the  reagents  used  in  the  standardization,  to  determine 
how  much  molybdate  solution  is  required  to  give  the  yellow  color 
to  the  tannin  when  no  lead  is  present.  This  amount  is  to  be 
deducted  from  all  titrations. 

Pb  in  Ore.  Weigh  0.5  gm.  of  ore  (1  gm.  if  it  contains  less 
than  30  per  cent  lead),  and  transfer  it  to  a  200-cc.  Erlenmeyer 
flask.  Add  10  cc.  of  hydrochloric  acid  and  boil. 

Hydrochloric  acid  attacks  galena,  ferric  oxide,  etc. 

Continue  boiling  and  add,  at  short  intervals,  20  cc.  of  water, 
10  cc.  of  nitric  acid,  and  10  cc.  of  dilute  sulphuric  acid  (1  :  1). 

Nitric  acid  is  added  to  attack  those  sulphides  not  dissolved  by  hydro- 
chloric acid. 

Boil  over  the  open  flame  (see  p.  169)  until  dense  sulphuric 
acid  fumes  are  evolved.  Cool,  add  25  cc.  of  cold  water,  heat 
to  the  boiling-point,  and  let  it  stand  to  dissolve  ferric  sulphate. 
Cool,  filter,  and  wash  the  residue  with  dilute  sulphuric  acid 
(1  :  10),  and  then  with  water.  Spread  the  filter  paper  against 
the  inside  of  a  beaker,  (Fig.  52,  p.  61),  and  wash  off  the  pre- 
cipitate with  hot  water,  followed  by  hot  ammonium  acetate 
solution,  and  add  a  sufficient  amount  of  ammonium  acetate 
to  dissolve  all  the  lead  sulphate. 

One  part  of  lead  sulphate  is  soluble  in  47  parts  of  ammonium  ace- 
tate solution  of  specific  gravity  1.036. 

PbS04+2NH4C2H302=Pb(C2H3O2)2-i-(NH4)2SO4. 


LEAD  IN  ORE  177 

Heat  to  boiling  and  titrate  with  standard  solution  of  ammo- 
nium molybdate  until  a  drop  of  the  solution  titrated  tested  with 
a  drop  of  tannin  solution  on  a  porcelain  plate  gives  a  yellow 
color. 

LEAD  IN  ORE 

FIRE  METHOD  * 

This  method  for  the  assay  of  lead,  although  much  used,  is  in- 
accurate. It  gives  too  low  results  with  pure  ores,  and  too  high 
results  with  ores  containing  arsenic,  antimony,  bismuth,  etc. 

Flux.     Sodium  bicarbonate,  NaHCOs,  64  parts. 

Potassium  carbonate,  K^COs,  50  parts. 

Borax  glass,  Na2B4C>7,  25  parts. 

Flour,  25  parts.  The  reducing  power  of  the  flour  should  be 
tested,  and  if  found  to  be  below  3,  the  quantity  added  to  the 
flux  should  be  increased.  Mix  the  reagents  thoroughly  by 
rolling  on  a  rubber  cloth. 

Pb  in  Ore.  Weigh  10  gms.  of  ore  and  mix  it  in  a  crucible  (see 
Fig.  84,  page  225)  with  20  gms.  of  flux.  Cover  with  10  gms. 
of  flux,  and  if  the  ore  is  low  in  sulphur,  put  into  the  charge 
one  tenpenny  nail ;  if  it  is  high  in  sulphur,  put  in  two  tenpenny 
nails.  Put  the  crucible  into  a  muffle  heated  to  a  moderately  low 
temperature  and  raise  the  heat  to  a  light  yellow  and  fuse  for 
thirty  minutes. 

7PbS+4K2C03  =  4Pb+ K2S+3(K2S  -PbS)+4C02. 
PbS+Fe=Pb+FeS. 

2PbO+C=Pb+C02. 

When  the  fusion  is  complete,  withdraw  the  crucible  from 
the  muffle,  take  out  the  nails  with  a  pair  of  short  tongs,  taking 
care  to  shake  off  into  the  crucible  any  adhering  globules  of 
lead.  Shake  the  crucible  and  tap  it  gently  several  times  to 

*  See  Fire  Assaying,  page  224. 


178  METALLURGICAL  ANALYSIS 

concentrate  the  lead  in  the  bottom,  and  pour  the  fusion  into 
the  mold. 

When  cold,  break  the  slag  from  the  lead  button  and  weigh 
the  lead.  If  the  lead  button  is  hard  or  brittle,  it  is  alloyed  with 
other  metals  and  the  assay  is  not  accurate. 

ZINC  IN  ORE 

Outline.  The  ore  is  treated  with  hydrochloric  and  nitric 
acids,  then  with  potassium  chlorate  and  a  fresh  portion  of  nitric 
acid,  after  which  the  solution  is  evaporated  to  dryness.  The  residue 
is  treated  with  ammonia ,  ammonium  chloride,  bromine,  and  water; 
zinc  and  copper  are  taken  into  solution  and  are  filtered  from  the 
residue,  which  contains  the  other  metals  and  the  insoluble  part  of 
the  ore.  The  solution  is  then  acidified  with  hydrochloric  acid, 
the  cop~er  precipitated,  and  the  zinc  titrated  with  a  standard 
solution  of  potassium  ferrocyanide.* 

Reagents.     Potassium  chlorate,  KClOa. 

Ammonium  chloride,  NILiCl. 

Bromine  water;  water  saturated  with  Br. 

Standard  solution  of  potassium  ferrocyanide.  Dissolve  21.63 
gms.  K4Fe(CN)e  and  7  gms.  Na2SOs+7H2O  in  water,  and 
dilute  the  solution  to  1  liter.  One  cubic  centimeter  is  equiv- 
alent to  about  0.005  gm.  Zn.  To  standardize,  dissolve  0.2  gm. 
of  chemically  pure  zinc  or  freshly  ignited  chemically  pure  zinc 
oxide  in  15  cc.  of  hydrochloric  acid,  add  7  gms.  of  ammonium 
chloride,  dilute  to  200  cc.  with  boiling  water,  and  titrate,  using 
uranium  nitrate  solution  on  a  porcelain  plate  as  indicator. 

Indicators:  uranium  nitrate  solution;  1  gm.  U02(NO3)2+6H2O 
dissolved  in  10  cc.  of  water.  Other  indicators  are: 

Ammonium  molybdate  solution,  1  gm.  dissolved  in  100  cc. 
of  water;  or  a  saturated  solution  of  uranium  acetate. 

*  Sutton,  "Volumetric  Analysis,"  356.  Low,  "Tech.  Meth.  of  Ore  Anal.," 
210. 


ZINC  IN  ORE  179 

Run  a  blank  in  the  usual  manner  and  make  the  necessary 
correction. 

Zn  in  Ore.  Weigh  1  gm.  of  ore,  transfer  it  to  a  200-cc. 
Erlenmeyer  flask,  add  15  cc.  of  hydrochloric  acid,  and  boil. 
Add  25  cc.  of  nitric  acid  and  boil  down  to  a  volume  of  10  cc. 
Then  add  10  cc.  of  nitric  acid  and  5  gms.  of  potassium  chlorate, 
a  little  at  a  time.  Evaporate  just  to  dryness. 

A  high  heat  after  the  mass  is  dry  will  volatilize  zinc  chloride. 

Cool,  add  10  gms.  of  ammonium  chloride,  15  cc.  of  ammonia, 
25  cc.  of  water,  and  10  cc.  of  bromine  water. 

Instead  of  adding  ammonium  chloride,  ammonia,  and  bromine 
water,  Demorest  *  precipitates  Fe,  Mn,  Pb,  and  Cd  by  adding  0.5 
gm.  KOH  and  7  gms.  (NH4)2C03  with  50  cc.  H20,  filtering,  dissolving 
the  precipitate  in  HC1,  reprecipitating  in  the  same  manner  and  filter- 
ing. 

Boil  two  minutes,  filter,  and  wash  well  with  a  hot  solution 
of  ammonium  chloride  (10  gms.  NH4Cl+2  drops  NH4OH  +  1000 
cc.  of  water). 

Acidify  the  filtrate  with  hydrochloric  acid,  dilute  to  150  cc., 
add  20  gms.  of  granulated  lead;  and  boil  to  precipitate  copper. 
Remove  from  the  heat,  dilute  again  to  150  cc.  with  water,  heat  to 
70°  C.  and  titrate  immediately  with  a  standard  solution  of 
potassium  ferrocyanide.  (See  zinc  in  matte,  p.  186.) 

Hydrogen  sulphide  may  be  used  as  the  precipitant  of  copper  instead 
of  granulated  lead.  If  no  copper  is  present,  this  step  may  be  omitted. 

The  solution,  when  titrated,  should  be  at  about  70°  C.,  and  there 
should  be  an  excess  of  about  3  cc.  of  hydrochloric  acid  in  the  whole 
volume  of  150  cc. 

*  J.  Ind.  and  Eng.  Chem.,  5,  302. 


180  METALLURGICAL  ANALYSIS 

ARSENIC 
SKINNER  AND  HAWLEY'S  METHOD 

Reagents.      Hydrogen    sulphide-,      H2S    from    a    generator. 

Sodium  sulphite,  Na2SOs. 

Distilling  solution:  Mix  500  cc.  of  water  with  1200  cc.  of 
hydrochloric  acid  (sp.gr.  1.2),  add  the  mixture  gradually  to  400 
gms.  of  pure  zinc,  and  heat  to  dissolve  the  zinc.  Evaporate  the 
solution  to  1100  cc.  and  add  to  it  a  solution  of  300  gms.  of  pure 
cupric  chloride  crystals  in  1  liter  of  hydrochloric  acid  (sp.gr.,  1.2). 

Sodium  bicarbonate,  NaHCOs. 

Starch  solution.     (See  p.  111). 

Standard  iodine  solution.  Weigh  16.932  gms.  of  pure  iodine. 
Transfer  it  to  a  liter  flask,  add  30  gms.  of  potassium  iodide,  add 
water,  and  when  the  iodine  is  dissolved,  dilute  the  solution 
to  1  liter.  One  cubic  centimeter  should  be  equivalent  to  about 
0.005  gm.  of  arsenic. 

The  solution  may  be  standardized  by  weighing  accurately 
about  0.2  gm.  As203,  dissolving  it  in  dilute  hydrochloric  acid, 
neutralizing  with  ammonia,  just  acidifying  the  solution  with 
hydrochloric  acid,  and  adding  sodium  bicarbonate  and  starch 
solution,  and  titrating  with  the  iodine  solution. 

As  in  Ores  and  Furnace  Products.  Weigh  0.5  gm.  of  the  sample 
(if  the  material  is  low  in  arsenic,  as  much  as  5  gms.  may  be  used) 
and  transfer  it  to  a  small  beaker.  Add  5  cc.  of  nitric  acid  and 
a  little  potassium  chlorate.  When  vigorous  action  has  ceased, 
add  8  cc.  of  hydrochloric  acid  and  evaporate  the  solution  to  dry- 
ness  at  about  100°  C.  Add  5  cc.  of  hydrochloric  acid  and  25 
cc.  of  water,  boil,  and  filter.  Dilute  the  filtrate  to  200  cc.  with 
boiling  water.  Add  sodium  sulphite,  a  little  at  a  time,  until 
the  solution  becomes  colorless. 

As2Os+3H20+2Na2S03=2As(OH)3+2Na2SC>4. 
Na2S03+2HCl  =2NaCl+H20+S02. 


ARSENIC 


181 


Boil  off  the  excess  of  SOo,  add  15  cc.  of  hydrochloric  acid, 
and  pass  a  current  of  hydrogen  sulphide  through  the  solution 
until  the  sulphides  are  completely  precipitated. 

2As(OH)3+3H2S  =6H2O+As2S3. 

If  there  are  present  only  small  quantities  of  other  hydrogen  sul- 
phide metals,  the  precipitation  of  the  arsenic  is  hastened  by  adding, 
to  the  sample  0.1  gm.  of  pure  copper. 

Filter  and  wash  the  sulphide.  Place  the  pre- 
cipitate in  a  flask  fitted  with  a  thermometer  and 
connected  with  a  condenser  (8-in.  Allihn,  Fig.  79,  is 
satisfactory),  add  50  cc.  of  distilling  solution,  and 
distil  carefully  until  the  thermometer  reads  115°  C., 
letting  the  distillate  run  into  a  flask  which  con- 
tains dilute  sulphuric  acid  (1  :  20).*  Remove  from 
the  heat  and  add  25  cc.  of  hydrochloric  acid,  and 
distil  again  until  the  thermometer  reads  115°  C. 

As2S3+3CuCl2  =2AsCl3+3CuS. 

2AsCl3+6H2O  =  2As(OH)3+6HCl  FlG-  79.— Al- 

lihn   Con- 

Arsenious  trichloride  is  volatile  when  boiled  in  a  con-      denser, 
cent  rated  solution  of  hydrochloric  acid. 

Pour  the  distillate  into  a  No.  3  beaker.  Add  ammonia  until 
the  solution  is  alkaline;  then  just  acidify  it  with  dilute  sul- 
phuric acid.  Cool,  add  about  10  gins,  of  sodium  bicarbonate, 
4  drops  of  a  10  per  cent  solution  of  KI,  and  a  little  starch  solu- 
tion, and  titrate  with  standard  iodine  solution. 

2As(OH)3+4I+4NaHC03=As206+4NaI+5H20+4C02. 

Sodium  bicarbonate  must  be  used,  since  the  hydroxyl  ion  resulting 
from  the  use  of  caustic  or  neutral  alkali  reacts  with  iodine. 

*  Price  and  Meade,  "  Tech.  Anal,  of  Brass,"  p.  257. 


182  METALLURGICAL  ANALYSIS 


ARSENIC  IN  INSOLUBLE  ORES  AND  FURNACE 
PRODUCTS.* 

Reagents.  Sodium  carbonate,  Na^COs,  and  potassium 
nitrate,  KNOs,  mixed  in  equal  parts. 

Acetic  add,  C2H402,  (sp.gr.  1.04). 

Solution  of  phenolphthalein.     (See  p.  84.) 

Solution  of  sodium  hydroxide.  Dissolve  10  gms.  NaOH  in 
100  cc.  of  water. 

Saturated  solution  of  silver  nitrate  (AgNOs)  in  water. 

Granulated  lead,  Pb. 

As  in  Ore.  Weigh  0.5  gm.  of  the  sample,  mix  it  with  3  gms. 
of  the  sodium  carbonate  and  potassium  nitrate  flux.  Transfer 
the  mixture  to  a  porcelain  crucible,  and  add  as  a  cover  2  gms. 
of  the  same  fusion  mixture.  Gradually  raise  the  temperature 
and  fuse  for  a  few  minutes. 

As+3KN03  =K3As04+2N02+NO. 

Cool,  treat  the  fusion  with  hot  water,  and  filter.  Strongly 
acidify  the  filtrate  which  contains  the  arsenic,  with  acetic  acid. 
Boil  to  expel  C02.  Cool,  add  a  few  drops  of  phenolphthalein 
solution,  and  make  alkaline  with  sodium  hydroxide  solution. 
Acidify  with  acetic  acid,  add  a  slight  excess  of  silver  nitrate  solu- 
tion and  stir  vigorously. 

K3As04+3AgNO3  =3KN03-fAg3As04. 

Let  the  precipitate  settle  away  from  direct  sunlight.  Filter, 
and  wash  by  decantation  with  cold  water.  Transfer  the  pre- 
cipitate to  the  filter  and  wash  it  well.  Place  the  filter  with  pre- 
cipitate in  a  scorifier,  dry,  add  granulated  lead  and  borax,  and 
make  a  scorification  assay  for  silver.  (See  p.  234.)  The  weight 

*  Bennett,  Jour.  Amer.  Chem.  Soc.,  21,  431. 


ARSENIC  IN  ORE  183 

of  silver,  multiplied  by  the  factor  0.2316,  will  give  the  weight 
of  arsenic. 

Wt.  Ag.  :  Wt.  As.  =  3(107.88)  :  74.96. 

If  the  ore  contains  soluble  chlorides,  they  must  be  washed  out 
before  making  the  fusion. 

ARSENIC  IN  ORE  BY  TITRATING  WITH  AMMO- 
NIUM THIOCYANATE 

After  obtaining  the  precipitate  of  Ag3AsO4,  according  to  the 
method  above,  instead  of  determining  the  silver  by  a  scorification 
assay,  it  may  be  determined  as  follows:  Dissolve  the  precipitate 
of  AgsAsOd  in  dilute  nitric  acid. 

This  leaves  silver  chloride,  if  present,  undissolved. 

Ag3As04+3HN03  =  3AgN03+H3As04. 

Filter,  add  5  cc.  of  a  saturated  solution  of  ammonium  ferric 
sulphate,  as  indicator,  and  titrate  with  a  standard  solution  of 
ammonium  thiocyanate  until  brown  ferric  thiocyanate  remains 
after  shaking. 

AgN03+NH4CNS  =AgCNS+NH4NO3. 

When  the  silver  thiocyanate  has  all  been  precipitated,  the  ammonium 
thiocyanate  then  combines  with  the  ammonium  ferric  sulphate  to  form 
brown  ferric  thiocyanate. 

Fe2(S04)3+6NH4CNS=2Fe(CNS)3-f3(NH4)2S04. 

The  ammonium  thiocyanate  solution  is  standardized  against  silver 
nitrate. 


184  METALLURGICAL  ANALYSIS 

ANALYSIS   OF  COPPER   MATTE 

COPPER  IN  MATTE 
ELECTROLYTIC  METHOD 

Weigh  1  gm.  of  matte  and  transfer  it  to  a  No.  4  beaker. 
Moisten  it  with  a  few  drops  of  water,  add  8  cc.  of  nitric  acid 
and  1  cc.  of  sulphuric  acid.  Evaporate  the  solution  to  dryness. 
Dissolve  the  residue  in  8  cc.  of  nitric  acid.  Dilute  the  solution, 
filter,  and  electrolyze.  (See  Copper  in  Ore,  p.  173.) 

COPPER  IN  MATTE 
POTASSIUM  IODIDE   METHOD 

Weigh  0.5  gm.  of  matte,  transfer  it  to  a  150-cc.  Erlenmeyer 
flask,  add  5  cc.  of  nitric  acid,  and  heat  until  the  mass  is  pasty 
and  red  fumes  have  ceased  to  come  off.  Remove  from  the  heat, 
add  15  cc.  of  water,  and  boil  five  minutes.  Add  ammonia  to 
make  the  solution  slightly  alkaline,  boil  out  the  excess  of  ammonia, 
remove  from  the  heat,  make  strongly  acid  with  acetic  acid,  and 
cool.  When  cold,  add  3  gms.  of  potassium  iodide,  shake,  and 
titrate  at  once  with  standard  sodium  thiosulphate  solution  until 
the  yellow  color  begins  to  fade.  Add  20  cc.  of  starch  solution 
and  continue  the  titration  until  the  bluish  green  color  disappears 
and  does  not  return  for  ten  seconds. 

For  reagents  and  notes  see  Copper  in  Ore,  p.  171. 

Owing  to  impurities  in  the  matte,  the  end-point  is  not  permanent 
and  a  little  experience  is  required  to  enable  the  operator  to  detect  the 
correct  end. 


COPPER  IN  MATTE  185 

COPPER  IN  MATTE 

POTASSIUM  CYANIDE  METHOD 

Weigh  0.5  gm.  of  matte,  transfer  it  to  a  small  Erlenmeyer 
flask,  add  5  cc.  of  nitric  acid,  and  proceed  according  to  the  potas- 
sium cyanide  method  for  copper  in  ore  (see  p.  168) ;  or  the  some- 
what more  rapid  method  given  below  may  be  used. 

Weigh  0.5  gm.  of  the  matte  and  transfer  it  to  a  small  beaker. 
Add  15  cc.  of  nitric  acid  and  boil  ten  minutes.  Remove  from  the 
heat,  add  35  cc.  of  cold  water,  and  make  the  solution  strongly 
alkaline  with  ammonia  to  precipitate  the  iron.  Filter  rapidly, 
wash  the  precipitate  back  into  the  original  beaker  with  as  little 
hot  water  as  possible,  and  redissolve  in  as  small  quantity  as 
possible  of  dilute  sulphuric  acid  (1  :  3).  Reprecipitate  the  iron 
with  ammonia  and  filter,  letting  this  filtrate  run  into  the  first 
filtrate.  Wash  well  with  hot  water,  cool,  and  titrate  with  a 
standard  solution  of  potassium  cyanide.  (See  p.  168.) 

IRON  IN  MATTE 

POTASSIUM  BICHROMATE  METHOD 

Weigh  0.5  gm.  of  matte,  transfer  it  to  a  small  beaker,  add 
15  cc.  of  nitric  acid,  dissolve  at  a  moderate  heat,  and  evaporate 
the  solution  to  dryness.  When  free  from  nitrous  fumes,  cool, 
add  25  cc.  of  hydrochloric  acid,  cover  with  a  watch  glass,  and 
heat  until  the  solution  is  clear  and  globules  of  sulphur  float  on 
the  surface.  Add  25  cc.  of  hot  water  and  about  20  gms.  of 
granulated  lead,  and  boil  until  the  copper  is  precipitated  on  the 
lead  and  the  ferric  chloride  is  reduced  to  ferrous  chloride,  leaving 
the  solution  clear.  Remove  from  the  heat  and  wash  all  particles 
of  test  lead  to  the  bottom  of  the  beaker.  Decant  the  solution 
into  a  beaker,  wash  the  lead  with  hot  water  by  decantation, 
cool  the  solution  to  the  temperature  of  the  room,  and  titrate 
with  a  standard  solution  of  potassium  dichromate.  (See  Iron 
in  Ores,  p.  62.) 


186  METALLURGICAL  ANALYSIS 


ZINC  IN  MATTE 

Reagents.     See  Zinc  in  Ore  (p.  178). 

Weigh  0.5  gm.  of  matte,  •  transfer  it  to  a  small  beaker,  add 
20  cc.  of  chlorate  solution  (saturated  solution  of  KClOs  in  HNOs, 
sp.gr.  1.42).  Heat  to  dissolve,  and  evaporate  the  solution  at 
a  moderate  heat  to  dryness.  Add  about  10  gms.  of  ammonium 
chloride,  25  cc.  of  ammonia,  and  25  cc.  of  boiling  water.  Cover, 
and  boil  two  minutes.  Filter  and  wash  well  with  a  hot  solu- 
tion of  ammonium  chloride  (10  gms.  NH4C1+2  drops  of  NELiOH 
+  1000  cc.  of  water).  Acidify  the  filtrate  with  hydrochloric 
acid,  dilute  the  solution  to  150  cc.,  add  20  gms.  of  granulated 
lead,  and  boil  until  the  copper  is  all  precipitated  on  the  lead 
and  the  solution  is  clear.  Remove  from  the  heat  and  dilute 
again  to  150  cc.  with  cold  water  and  titrate  immediately  with 
a  standard  solution  of  potassium  ferrocyanide,  using  a  solution 
of  uranium  nitrate  or  acetate  as  indicator.  (See  p.  178.) 

White  titrating,  if  a  brownish  or  red  precipitate  forms,  it  indicates 
that  the  solution  was  not  boiled  long  enough  with  the  granulated  lead 
to  precipitate  all  the  copper,  and  the  determination  must  be  discarded. 


LEAD  IN  MATTE 

Reagents.     See  Reagents  for  Lead  in  Ore  (p.  175). 

Weigh  0.5  gm.  of  matte  and  transfer  it  to  a  250-cc.  Erlenmeyer 
flask,  add  10  cc.  of  hydrochloric  acid,  and  heat  to  boiling.  Add 
5  cc.  of  nitric  acid  and  7  cc.  of  sulphuric  acid  and  boil  over  the 
open  flame  of  the  Bunsen  burner  (see  p.  169)  until  dense  white 
fumes  of  sulphuric  acid  are  given  off  freely  and  the  volume  is 
reduced  to  only  a  few  cubic  centimeters.  It  is  essential  that  all 
the  nitric  acid  be  expelled. 

Cool,  add  50  cc.  of  cold  water,  heat,  and  let  the  solution 
stand  at  the  boiling-point  five  minutes.  Filter,  and  wash  well 
with  hot  water.  Spread  out  the  filter  paper  with  its  contents 


SULPHUR  IN  MATTE  187 

on  the  inside  of  a  beaker  and  wash  off  the  precipitate  with  a 
jet  of  hot  water,  using  about  25  cc.;   discard  the  filter  paper. 

Pour  20  cc.  of  a  saturated  solution  of  ammonium  acetate 
into  the  flask  in  which  the  precipitation  was  made,  shake  to 
dissolve  any  adhering  lead  sulphate,  and  pour  the  solution  into 
the  beaker  containing  the  main  precipitate  of  lead  sulphate. 
Wash  out  the  flask,,  using  about  25  cc.  of  hot  water,  and  add  it 
to  the  lead  sulphate  solution.  Heat  the  solution  to  boiling  and 
titrate  it  hot  with  the  standard  solution  of  ammonium  molybdate, 
using  tannin  solution  as  an  indicator,  (See  p.  176.) 

SULPHUR  IN  MATTE 

Weigh  0.5  gm.  of  the  matte  and  transfer  it  to  a  porcelain 
casserole.  Sprinkle  1  gm.  of  potassium  chlorate  over  the  sample, 
add  15  cc.  of  chlorate  solution  (saturated  solution  of  KClOa 
in  strong  nitric  acid),  cover,  and  keep  it  cool  until  the  sulphur  is 
oxidized.  Heat  gradually  and  evaporate  slowly  to  dryness. 
When  thoroughly  dry,  cool,  add  25  cc.  of  water  and  15  cc. 
hydrochloric  acid  and  boil  until  the  solution  is  clear.  Filter  hot 
and  wash  with  hot  water.  Add  5  cc.  of  a  saturated  solution  of 
barium  chloride  and  heat  to  the  boiling-point. 

If  the  matte  contains  much  lead,  boil  at  least  five  minutes  to  dissolve 
lead  chloride,  and  filter  hot  to  prevent  the  contamination  of  barium 
sulphate  with  lead  chloride. 

Remove  from  the  heat  and  let  the  barium  sulphate  settle. 
Filter,  wash  with  hot  water,  burn  in  an  annealing  cup  in  a  muffle, 
or  in  a  platinum  crucible  and  weigh.  The  factor  for  S  in  BaSCU 
is  0.13738. 

MANGANESE  IN  MATTE 

Weigh  0.5  gm.  of  matte  and  transfer  it  to  a  small  beaker. 
Add  35  cc.  of  water,  boil,  add  15  cc.  of  hydrochloric  acid,  and 
boil  ten  minutes.  Add  5  cc.  of  nitric  acid  and  continue  boiling 


188  METALLURGICAL  ANALYSIS 

ten  minutes.  Remove  the  beaker  from  the  heat,  add  an  emulsion 
of  zinc  oxide  until  the  solution  when  stirred  is  almost  white. 
Dilute  the  solution  to  150  cc.  with  hot  water,  heat  to  the  boiling- 
point,  and  titrate  hot,  according  to  the  Volhard  method,  with 
a  standard  solution  of  potassium  permanganate.  (See  p.  88.) 

GOLD  AND  SILVER  IN  MATTE 

Weigh  0.1  assay-ton.  Place  it  in  a  scorifier,  add  70  gms.  of 
granulated  lead,  a  little  borax  glass,  and  a  little  silica.  Place 
the  scorifier  in  a  hot  muffle.  After  melting,  reduce  the  tem- 
perature and  complete  the  scorification  at  a  moderate  tem- 
perature. Cupel  the  lead  button,  weigh  the  bead  of  silver  com- 
bined with  gold,  part  in  the  usual  way  with  nitric  acid,  and  weigh 
the  gold.  The  difference  between  the  weight  of  gold  and  the 
combined  weight  of  gold  and  silver  will  give  the  weight  of  silver. 
(See  Fire  Assaying,  p.  224.) 

ANALYSIS  OF  CHILLED  BLAST  FURNACE  SLAGS 

Sampling.  Granulate  the  slag  by  dipping  a  sample  from 
the  molten  slag  with  an  iron  ladle  and  pouring  it  into  a  pail  of  water. 
Then  take  out  the  granulated  slag  with  the  ladle  and  place  it 
near  the  heat  to  dry.  When  the  slag  is  dry,  crush  it  and  prepare 
the  sample  for  analysis  in  the  usual  way.  (See  p.  8.) 

SILICA  IN  SLAG 

Weigh  0.5  gm.  of  slag  and  transfer  it  to  a  casserole.  Moisten 
it  with  a  few  drops  (6  or  7)  of  water.  Stir  with  a  glass  rod,  and 
while  stirring  add  slowly  about  4  cc.  of  hydrochloric  acid.  Con- 
tinue stirring  until  the  slag  gelatinizes. 

The  slag  is  treated  first  with  hydrochloric  acid  alone  to  insure  the 
escape  of  sulphur  as  ELS.  If  nitric  acid  were  added  at  the  same  time, 


LIME  IN  SLAG  189 

the  EUS  would  be  oxidized  and  would  combine  with  barium  to  form 
barium  sulphate,  which  would  come  down  with  the  SiO-2. 

Add  about  1  cc.  of  nitric  acid  and  stir,  spreading  the  gelatinous 
precipitate  smoothly  on  the  inside  of  the  casserole. 

This  permits  rapid  dehydration  without  loss. 

Nitric  acid  is  added  to  oxidize  the  lead  and  copper  sulphides,  which 
are  not  completely  decomposed  by  hydrochloric-  acid.  The  lead  will 
be  dissolved  by  the  hot  acids  and  pass  through  the  filter. 

Take  the  cover  off  the  casserole  and  heat  until  the  acid  has 
all  evaporated. 

Do  not  prolong  the  heating  at  too  high  a  temperature,  since 
there  is  danger  of  recombining  some  of  the  silica  with  alumina, 
giving  a  gray-colored  residue  after  ignition,  and  a  high  result. 

Cool  the  casserole,  add  about  15  cc.  of  hydrochloric  acid, 
and  boil.  Dilute  with  a  little  hot  water  and  filter  hot.  Wash 
the  precipitate  with  hot  water  until  it  is  free  from  chlorides. 

The  residue  may  be  black,  owing  to  the  presence  of  carbon. 

Place  the  filter  and  residue  in  a  porcelain  crucible,  burn  fifteen 
minutes  in  a  hot  muffle,  cool,  and  weigh. 

By  this  method  the  result  is  insoluble  silicious  residue,  but  it  is  usually 
reported  as  silica,  unless  a  fusion  silica  is  especially  asked  for.  In  the 
latter  case,  follow  the  method  for  silica  in  ore,  page  71,  or  purify  the 
insoluble  silicious  residue  with  hydrofluoric  and  sulphuric  acids. 


LIME  IN  SLAG 

Add  to  the  filtrate  from  the  silica,  which  should  measure 
about  150  cc.,  ammonia  in  slight  excess.  Add  just  enough  hot 
saturated  solution  of  oxalic  acid  to  dissolve  the  iron  precipitate. 
Add  ammonia  again  until  a  slight  precipitate  of  iron  is  obtained, 
and  then  add  oxalic  acid  to  dissolve  the  iron.  There  should  now 
be  a  white  precipitate  of  calcium  oxalate,  and  the  solution  should 
be  slightly  acid,  and  should  have  a  clear  greenish-yellow  color. 


190  METALLURGICAL  ANALYSIS 

Boil,  and  let  the  precipitate  settle  ten  minutes  or  more.  Filter, 
wash  the  precipitate  once  by  decantation  with  hot  water,  and 
then  wash  it  on  the  filter  until  all  the  oxalic  acid  is  removed. 

Test  the  wash  water  for  oxalic  acid  by  collecting  a  few  cubic  centi- 
meters as  it  runs  from  the  funnel,  heating  it  and  adding  a  little  sulphuric 
acid,  and  a  drop  of  potassium  permanganate  solution.  If  the  color 
of  the  permanganate  fades,  oxalic  acid  is  present  and  the  washing  must 
be  continued  and  the  test  repeated  until  no  oxalic  acid  remains. 

Spread  the  filter  paper,  with  the  precipitate,  on  the  inside 
of  a  beaker.  Wash  the  precipitate  from  the  paper  with  200 
cc.  of  hot  water,  using  a  strong  jet  from  a  wash  bottle.  Add  40 
cc.  of  dilute  sulphuric  acid  (1:1).  Stir  to  dissolve  the  pre- 
cipitate and  titrate  the  hot  solution  with  standard  potassium 
permanganate  solution. 

For  reactions  and  method  of  calculating  the  result,  see  Lime  in  Lime- 
stone, page  163. 

IRON  IN  SLAG 

Weigh  0.5  gm.  of  slag,  transfer  it  to  a  small  beaker,  add 
30  cc.  of  water,  cover,  and  boil.  While  boiling,  add  20  cc.  of 
hydrochloric  acid  and  continue  to  boil  until  the  solution  is  clear. 
Add  2  or  3  drops  of  stannous  chloride  solution  to  the  hot  solu- 
tion and  stir.  Cool,  and  when  cold  add  20  cc.  of  mercuric 
chloride  solution  and  titrate  with  standard  potassium  dichromate 
solution.  (See  Iron  in  Ore,  p.  62.) 

MAGNESIA  IN  SLAG 

Weigh  0.5  gm.  of  slag  and  treat  it  according  to  the  method 
for  the  determination  of  silica.  To  the  filtrate  from  the  silica 
add  an  excess  of  ammonia,  and  ammonium  chloride.  Add  10 
cc.  of  bromine  water  and  0.03  gm.  of  ammonium  persulphate 
for  every  0.01  gm.  of  manganese  in  the  solution.  Boil  to  pre- 
cipitate iron,  alumina,  and  manganese.  Filter,  redissolve  the 


MANGANESE  IN   SLAG  191 

precipitate   in   hydrochloric   acid,    and   add   ammonia,   bromine 
water,  and  ammonium  persulphate,  as  before.     Boil  and  filter. 

Combine  the  nitrates  and  add  ammonium  oxalate  to  precipitate 
calcium.  Filter,  and  wash  the  precipitate  well.  To  the  filtrate 
add  a  solution  of  sodium  phosphate,  or  microcosmic  salt,  and 
proceed  according  to  the  method  for  the  determination  of 
magnesia  in  limestone.  (See  p.  165.) 

MANGANESE  IN  SLAG 

Weigh  0.5  gm.  of  the  slag  and  transfer  it  to  a  small  beaker. 
Add  30  cc.  of  water  and  20  cc.  of  hydrochloric  acid.  Boil  until 
the  solution  is  clear.  Add  5  cc.  of  nitric  acid  and  boil  five  minutes. 
Remove  from  the  heat  and  add  very  slowly,  while  stirring  vig- 
orously, an  emulsion  of  zinc  oxide,  and  proceed  according  to 
Volhard's  method  for  manganese  in  matte.  (See  p.  187.) 

ALUMINA  IN  SLAG 

Weigh  0.5  gm.  of  slag  and  treat  it  according  to  the  method 
for  the  determination  of  silica.  To  the  filtrate  from  the  silica 
add  ammonia  to  distinct  alkaline  reaction.  Boil  fifteen  minutes 
and  filter  to  remove  the  small  amount  of  copper  present.  Spread 
the  filter  paper,  with  the  precipitate,  against  the  inside  of  a 
beaker,  wash  off  the  precipitate  with  a  jet  of  hot  water,  dissolve 
in  hydrochloric  acid,  dilute  the  solution  to  400  cc.,  and  proceed 
according  to  the  phosphate  method  for  alumina.  (See  p.  87.) 

ZINC  IN  SLAG 

Weigh  0.5  gm.  of  slag  (if  low  in  zinc,  weigh  1  gm.),  transfer  it  to 
a  casserole,  add  3  cc.  of  water,  5  cc.  of  hydrochloric  acid,  and  2  cc. 
of  nitric  acid.  Stir,  and  when  completely  gelatinized,  add  4 
gms.  of  ammonium  chloride  and  stir.  Evaporate  just  to  dryness. 

Heating  at  a  high  temperature  when  dry  will  volatilize  zinc  chloride. 


192  METALLURGICAL  ANALYSIS 

Remove  from  the  heat  and  add  30  cc.  of  water.  Boil,  filter, 
and  wash  well  with  boiling  water.  Add  to  the  filtrate  0.03  gm. 
of  ammonium  persulphate  and  10  cc.  of  bromine  water  for  every 
0.01  gm.  of  manganese  in  the  solution.  Then  add  a  slight  excess  of 
ammonia.  Boil  a  few  minutes,  filter,  and  wash  with  a  solution  of 
ammonium  chloride  (100  gms.  NH4C1+50  cc.  NH4OH+1000  cc. 
H20).  Redissolve  the  precipitate  in  dilute  hydrochloric  acid, 
add  ammonium  persulphate,  bromine  water,  and  ammonia, 
as  before.  Boil  and  filter.  Combine  the  two  filtrates,  neutralize 
with  hydrochloric  acid,  and  add  5  cc.  in  excess.  Add  2  gms. 
of  granulated  lead  and  boil  fifteen  minutes.  Add  10  cc.  of 
hydrochloric  acid  and  titrate  at  a  temperature  of  60°  C.  with 
a  standard  solution  of  potassium  ferrocyanide.  (See  the  method 
for  zinc  in  ore,  p.  178.) 

LEAD  IN  SLAG 

Weigh  5  gms.  of  slag,  transfer  it  to  a  casserole,  add  10  cc.  of 
water,  stir  and  add  10  cc.  of  hydrochloric  acid,  and  continue 
stirring  until  the  slag  is  gelatinized.  Add  5  cc.  of  nitric 
acid.  Slowly  increase  the  heat,  stirring  to  break  up  lumps,  and 
gradually  evaporate  the  mass  to  dryness.  When  thoroughly 
dehydrated  continue  the  heat  a  few  minutes  until  the  mass  turns 
dark  brown.  Cool,  add  20  cc.  of  water  and  15  cc.  of  hydrochloric 
acid.  Boil  at  least  ten  minutes.  Filter  while  hot  and  let  the 
filtrate  run  into  a  500-cc.  beaker.  Dilute  the  filtrate  to  400 
cc.,  add  15  gms.  of  ammonium  chloride,  and  add  ammonia 
very  slowly,  stirring,  until  the  solution  becomes  dark  cherry 
red,  without  the  precipitation  of  iron.  Pass  hydrogen  sulphide 
through  the  solution  for  half  an  hour.  Filter,  spread  the  filter 
paper,  with  the  precipitate,  against  the  inside  of  a  beaker,  and 
wash  off  the  precipitate  with  as  little  hot  water  as  possible. 
Drop  10  cc.  of  nitric  acid  on  the  paper  and  wash  off,  with  water, 
all  traces  of  the  precipitate.  Remove  the  paper,  add  to  the 
solution  5  cc,  of  hydrochloric  acid  and  10  cc,  of  sulphuric  acid. 


COPPER  IN  SLAG  193 

Boil  the  solution  until  dense  white  fumes  of  sulphuric  acid  are 
evolved.  Cool,  dilute  with  40  cc.  of  cold  water,  boil  five  minutes, 
filter  the  lead  sulphate,  and  wash  it  with  hot  water.  Wash 
the  lead  sulphate  back  into  the  beaker  with  40  cc.  of  hot  water. 
Add  15  cc.  of  a  saturated  solution  of  ammonium  acetate.  Heat 
the  solution  to  boiling,  and  titrate  it  while  hot  with  standard 
solution  of  ammonium  molybdate.  (See  the  method  for  lead  in 
ore,  p.  175.) 

COPPER  IN  SLAG 

POTASSIUM  IODIDE  METHOD 

To  the  filtrate  from  the  precipitate  of  lead  sulphate  (see  the 
method  above),  add  15  cc.  of  a  saturated  solution  of  sodium 
thiosulphate  and  boil  until  the  sulphides  are  precipitated  and 
the  solution  is  clear.  Filter,  place  the  filter  paper,  with  the 
precipitate,  in  a  porcelain  annealing  cup,  and  burn  carefully 
at  a  very  low  heat  until  there  is  no  longer  a.  flame  of  burning 
sulphur.  Transfer  the  mass  to  a  flask,  and  add  a  little  potassium 
chlorate  and  5  cc.  of  nitric  acid.  Boil  until  the  solution  is  pasty. 
Add  20  cc.  of  water  and  boil  out  all  traces  of  nitrous  fumes.  Make 
the  solution  slightly  alkaline  with  ammonia,  boil  out  the  excess 
of  ammonia,  remove  from  the  heat,  and  acidify  with  acetic 
acid.  When  cold,  add  3  gms.  of  potassium  iodide  and  titrate 
with  a  standard  solution  of  sodium  thiosulphate.  (See  the  iodide 
method  for  copper  in  matte,  p.  184.) 

After  the  copper  sulphide  has  been  filtered  from  the  solution 
and  dissolved,  according  to  the  method  above,  instead  of  follow- 
ing the  iodide  method,  the  copper  may  be  measured  either  by 
electrolysis,  or  by  the  potassium  cyanide  method,  as  described 
for  the  determination  of  copper  in  matte.  (See  p.  185.)  The 
copper  may  also  be  determined  according  to  the  following  colori- 
metric  method. 


194  METALLURGICAL  ANALYSIS 

COPPER  IN  SLAG 

COLORIMETRIC    METHOD 

Weigh  3  gms.  of  the  sample,  moisten  it  with  water,  add  10  cc. 
of  nitric  acid  and  1  cc.  of  hydrochloric  acid,  and  heat  a  few 
minutes  on  a  steam  bath.  Dilute  with  100  cc.  of  water.  Add 
a  slight  excess  of  dilute  ammonia  (1:1)  and  filter  the  solution 
into  a  colorimetric  tube  or  bottle  and  wash  the  precipitate  free 
from  copper. 

For  a  standard,  weigh  3  gms.  of  a  sample  in  which  the  copper 
has  been  determined  electrolytically  and  treat  it  exactly  as 
described  above  for  the  unknown  sample.  Filter  the  solution 
into  a  similar  tube  or  bottle,  and  match  the  colors  in  a  colorim- 
eter, or  dilute  in  Eggertz  tubes. 

For  colorimetric  determinations  of  copper,  it  is  convenient  to  pre- 
pare a  set  of  standards,  increasing  in  strength  by  0.002  gm.  of  copper 
from  the  lowest  to  the  highest  required  for  low-grade  materials.  The 
unknown  solution  is  placed  in  a  bottle  similar  to  those  containing  the 
standards,  and  diluted  to  the  same  volume,  when  its  place  in  the  series 
is  easily  found  and  its  content  in  copper  determined  directly.  (See 
P.  42.) 

BARYTA  IN  SLAG 

Weigh  1  gm.  of  slag,  transfer  it  to  a  casserole,  add  potassium 
sulphate,  moisten  the  contents  of  the  casserole  with  water,  and 
add  nitric  and  hydrochloric  acids.  Heat  to  dissolve  the  slag, 
and  evaporate  the  solution  to  dryness.  Dissolve  the  residue 
in  dilute  hydrochloric  acid,  filter,  wash,  ignite,  and  weigh 
SiO2+BaSO4.  Deduct  the  SiC>2,  which  has  already  been  deter- 
mined in  the  slag,  and  multiply  the  remainder,  which  represents 
BaS04,  by  the  factor  for  BaO,  0.65699, 


ARSENIC  IN  SLAG  195 


ARSENIC  IN  SLAG 

Treat  5  to  10  gms.  of  the  slag  with  10  cc.  of  nitric  acid,  2  cc. 
of  sulphuric  acid,  and,  if  the  slag  has  not  been  chilled,  add  10  cc. 
of  hydrofluoric  acid.  Evaporate  the  solution  until  sulphuric 
acid  fumes  are  evolved.  Cool,  add  10  cc.  of  hydrochloric  acid 
and  25  cc.  of  water,  and  boil.  Filter,  wash,  and  dilute  the  fil- 
trate to  500  cc.  Add  ammonia  until  the  solution  is  almost 
neutral.  Reduce  with  sodium  sulphite  and  proceed  according 
to  the  method  for  arsenic  in  ores,  etc.,  on  page  180. 

ANALYSIS  OF  REVERBERATORY  SLAG 

SiO2  in  Slag.  Weigh  0.5  grn.  of  the  slag  and  transfer  it  to  a 
platinum  crucible  or  dish.  Add  about  6  gms.  of  sodium  carbonate, 
mix,  cover  with  1  or  2  gms.  of  sodium  carbonate  and  fuse.  Raise 
the  temperature  gradually  and  keep  the  crucible  at  a  bright  red 
heat  about  fifteen  minutes.  Cool  and  dissolve  the  fusion  in  a 
casserole  in  hydrochloric  acid  and  water. 

If  the  color  of  the  fusion  indicates  the  presence  of  much  manganese, 
the  fusion  should  be  dissolved  in  water  and  the  platinum  removed  from 
the  solution  before  the  addition  of  hydrochloric  acid.  The  platinum 
would  be  attacked  by  chlorine  liberated  from  the  hydrochloric  acid  by 
the  manganese. 

Evaporate  the  solution  to  dryness  to  dehydrate  the  silica. 
(See  p.  70.)  Cool,  add  10  cc.  of  hydrochloric  acid  and  30  cc. 
of  water  to  the  residue,  and  boil.  Filter,  wash,  ignite,  and 
weigh  Si02. 

FeO  in  Slag.  To  the  filtrate  from  the  silica,  add  a  slight 
excess  of  ammonia.  Boil,  filter,  and  wash.  Dissolve  the  pre- 
cipitate in  dilute  hydrochloric  acid,  reduce  the  iron  and  titrate 
it  according  to  the  method  for  iron  described  on  page  62.  The 
factor  for  converting  Fe  to  FeO  is  1.2865. 

CaO    in    Slag.     To  the  filtrate  from  the  hydrates  of  iron 


196  METALLURGICAL  ANALYSIS 

and  aluminum  obtained  in  the  method  for  FeO,  add  ammonium 
oxalate  and  a  little  ammonia.  Boil,  let  the  precipitate  settle, 
filter,  and  wash.  Dissolve  the  precipitate  of  calcium  oxalate 
in  sulphuric  acid  and  titrate  the  oxalic  acid  while  the  solution 
is  hot  with  standard  solution  of  potassium  permanganate.  (See 
p.  163.) 

Gold  and  Silver  in  Slag.  Gold  and  silver  are  determined  by 
crucible  assay.  Weigh  1  assay-ton,  transfer  it  to  a  fire-clay 
crucible,  and  mix  it  with  the  following  charge: 

gms. 

Litharge 80 

Sodium  bicarbonate 50 

Flour 3J 

(or  other  reducing  agent  to  yield  an  18-gm.  button). 

Mix  thoroughly  and  cover  with  borax.  Fuse  in  a  muffle  and 
complete  the  assay  according  to  the  method  given  on  page  229. 

ANALYSIS  OF  BRIQUETTES  AND    OTHER   INSOLUBLE 
COPPER-BEARING  PRODUCTS 

SiO2,  FeO,  and  CaO.  Weigh  0.5  gm.  of  the  sampie,  and 
transfer  it  to  a  casserole.  Add  6  cc.  of  hydrochloric  acid  and 
3  cc.  of  nitric  acid.  Cover  and  slowly  heat  to  boiling.  Dilute 
the  solution  with  boiling  water,  filter  into  a  casserole,  and  wash. 
Ignite  the  filter  in  an  annealing  cup  and  place  the  filtrate  on 
the  heat  to  evaporate. 

Mix  with  the  ignited  residue  in  the  annealing  cup  8  gms. 
of  sodium  carbonate  and  transfer  the  mixture  to  a  platinum 
crucible.  Cover  with  2  gms.  of  sodium  carbonate  and  pro- 
ceed with  the  fusion  according  to  the  method  above  for  the 
analysis  of  slag. 

When  the  filtrate  in  the  casserole  has  been  evaporated  to 
dryness,  dissolve  the  fusion  from  the  crucible  and  add  it  to  the 


ANALYSIS  OF  COPPER  BULLION  197 

casserole.  Evaporate  the  contents  of  the  casserole  to  dryness, 
and  proceed  with  the  determination  of  Si02,  FeO,  and  CaO 
according  to  the  method  described  above  for  the  analysis  of  slag. 

GOLD  AND  SILVER  IN  COPPER-BEARING  CONCEN- 
TRATES 

Mix  1  assay-ton  of  the  concentrates  in  a  fire-clay  crucible 
with  150  gms.  of  litharge,  35  gms.  of  sodium  bicarbonate,  10 
gms.  of  silica,  and  40  gms.  of  potassium  nitrate.  Cover  with 
salt  to  a  depth  of  half  an  inch,  fuse,  and  complete  the  assay 
according  to  the  method  given  on  page  229. 

ANALYSIS  OF  COPPER  BULLION 

Sampling.  At  the  furnace,  the  metal  is  sampled  in  the  molten 
condition  while  it  is  being  poured.  The  sample  is  taken  at 
regular  intervals;  the  first  is  taken  thirty  minutes  after  the  pour- 
ing begins,  and  the  others  at  intervals  of  an  hour,  by  batting  the 
stream  of  molten  metal  with  a  wooden  paddle,  driving  from 
150  to  200  gms.  of  the  molten  metal  into  a  pail  of  water,  where 
it  solidifies  in  the  form  of  shot.  The  samples  are  collected, 
mixed,  and  screened  through  a  4-mesh  screen,  and  then  through 
a  10-mesh  screen;  that  remaining  on  the  latter  is  reserved  for 
the  sample.  It  is  then  halved  with  a  riffle  and  one-half  of  the 
sample  is  sent  to  the  laboratory  for  analysis.* 

When  bullion  cools,  the  impurities  are  not  evenly  distributed 
throughout  the  mass,  but,  according  to  Keller, f  are  segregated, 
either  in  those  parts  which  cool  first,  if  the  impurities  are  high, 
or  in  those  parts  which  cool  last  if  the  impurities  are  low. 

Converter  copper,  having  more  than  97  per  cent  of  copper, 
usually  has  its  impurities,  including  gold  and  silver,  concentrated 

*  Wraith,  Trans.  Amer.  Inst.  Min.  Eng.,  41,  p.  318. 
t Trans.  Amer.  Inst.  Min.  Eng.,  27,  p.  106;  42,  p.  905. 


198 


METALLURGICAL  ANALYSIS 


in  that  part  which  cools  last;  while  black  copper,  from  the  blast 
furnace,  usually  has  its  impurities  concentrated  in  those  parts 
that  cool  first.  The  sampling  of  plates  and  bars,  therefore, 
requires  great  care.  This  is  best  done  by  taking  the  samples 
with  a  drilling-template.  For  sampling  anodes,  36.75  ins.  long, 

28  ins.  wide,  and  about  2  ins.  thick, 
Kellar  uses  a  99-hole  template  (Fig. 
80) .  Every  fourth  anode  in  the  lot 
is  sampled,  one  sample  being  taken 
from  each.  The  first  anode  is  care- 
fully swept,  the  template  laid  upon 
it,  and  drilled  through  with  a  J-in. 
drill  at  the  first  hole  in  the  tem- 
plate and  all  the  drillings  saved. 
The  succeeding  anodes  are  treated 
in  the  same  way,  the  holes  of  the 
template  being  used  in  consecutive 
order,  one  hole  to  the  anode.  The 
drillings  from  the  entire  lot  are 
then  ground  to  pass  through  a  16- 
The  sample  is  then  mixed  and  quartered.  The 
1  Ib.  is  screened  over  a  40-mesh  screen. 


-2ff.3}/ 


4  in.  Holes    ^    oj 


,1; 


FIG.  80. — Template  for  Sampling 
Anodes. 


mesh  screen. 

final  sample  of  about 

The  oversize  and  undersize  are  then  weighed  to  determine  the 

ratio  of   coarse  to  fine,  the  same  ratio  being  maintained  in  the 

assay-ton  made  up  for  analysis. 


MOISTURE  IN  PIG  COPPER 

When  copper  is  cast  into  pigs  in  a  casting  machine,  and  left 
to  cool  under  water,  the  water  is  taken  into  the  pores  of  the 
metal.  The  pores  are  so  small  that  the  ordinary  temperature 
at  which  moisture  is  determined  (100°  C.  to  110°  C.)  is  not  suf- 
ficient to  overcome  the  surface  tension  and  expel  it.  Therefore, 
the  sample  of  copper  in  which  moisture  is  to  be  determined  should 


COPPER  IN  COPPER  BULLION  199 

be  weighed  and  heated  to  about  200°  C.,  until  the  steam  is 
observed  to  escape  from  the  metal,  and  then  cooled  in  a  desiccator 
and  weighed  again.  The  loss  in  weight  represents  the  moisture. 

COPPER  IN  COPPER  BULLION  * 

Weigh  accurately  about  10  gms*  of  the  bullion  and  transfer 
it  to  a  beaker.  Add  a  drop  or  two  of  hydrochloric  acid  to  pre- 
cipitate silver.  Add  50  cc.  of  water  and  50  cc.  of  nitric  acid. 
When  in  solution,  let  the  silver  chloride  settle,  filter  into  a  care- 
fully weighed  flask,  and  dilute  with  water  to  about  300  cc.  Weigh 
the  flask.  This  requires  a  special  balance.  Take  out  about 
25  cc.  of  the  solution  and  reweigh  the  flask.  Dilute  the  portion 
taken  out  and  precipitate  the  copper  from  it  by  electrolysis. 
(See  electrolytic  method  for  copper,  p.  173.) 

SILVER  IN  COPPER  BULLION 

Weigh  one  assay-ton  (the  quantity  depends  upon  the  content 
of  silver).  Divide  it  into  ten  nearly  equal  parts  and  transfer 
each  part  to  a  beaker.  Dissolve  in  nitric  acid,  dilute,  and  add 
a  sufficient  amount  of  a  solution  of  sodium  chloride  to  precip- 
itate the  silver.  Let  the  silver  chloride  settle  over  night,  filter, 
place  the  filter  papers  with  their  contents  in  ten  scorifiers, 
sprinkle  with  litharge,  and  burn  the  papers,  Add  granulated 
lead  and  scorify.  (See  assay  of  silver  ores,  p.  234.)  Cupel, 
assemble  the  beads,  and  weigh.  Part  with  nitric  acid  and  weigh. 
The  difference  in  the  two  weights  represents  the  silver. 

*  This  method  for  copper  and  the  following  one  for  silver  were  com- 
municated to  the  author  by  D.  W.  Buckly,  Butte,  Mont. 


200  METALLURGICAL  ANALYSIS 

SILVER  IN  COPPER  BULLION 

WASHOE  METHOD 

Weigh  a  one  assay-ton  sample  of  the  drillings  and  transfer 
it  to  a  beaker.  Add  160  cc.  of  cold  water  and  110  cc.  of  nitric 
acid  (sp.gr.  1.42).  Cover;  when  in  solution,  wash  off  the 
cover,  add  100  cc.  of  cold  water  and  10  cc.  of  sodium  chloride 
solution  (2  gms.  NaCl  in  250  cc.  of  water). 

If  the  bullion  carries  more  than  100  ounces  of  silver  per  ton,  add  more 
sodium  chloride  solution. 

Stir,  and  let  the  precipitate  settle  twelve  hours.  Filter  and 
wash.  Wipe  out  the  beaker  with  pieces  of  filter  paper  and  add 
these  to  the  filter  containing  the  silver  chloride.  Place  the 
filter,  with  the  precipitate  of  silver  chloride,  on  a  scorifier,  add 
3  gms.  of  litharge,  and  burn  off  the  filter  in  a  muffle,  at  a  very 
low  temperature.  When  the  paper  is  burnt,  add  35  gms.  of 
granulated  lead  and  a  little  borax  glass,  and  scorify  at  a  low  heat. 
Cupel  and  weigh. 

Crush  the  top  of  the  cupel  containing  lead  oxide  on  a  bucking- 
board,  and  mix  it  in  a  crucible  with 

Gms. 

Sodium  carbonate 35 

Borax  glass . 60 

Litharge 30 

Calcium  fluoride 1 

Flour 5 

(or  other  reducing  agent  to  yield  a  15-gm.  button). 

Cover  with  borax  glass,  fuse  at  a  high  temperature,  and, 
after  separating  the  lead  button  from  the  slag,  cupel  and  weigh 
the  silver  bead,  and  add,  as  a  correction,  to  the  silver  already 
found.  (See  Fire  Assaying,  p.  224.) 


GOLD  IN  COPPER  BULLION  201 


GOLD  IN  COPPER  BULLION 

Weigh  10  portions  of  drillings,  each  1/20  of  an  assay-ton, 
place  each  portion  in  a  cupel,  38  mm.  in  diameter  and  28  mm. 
in  height.  Fill  the  cupel  with  test  lead,  place  it  in  a  very  hot 
muffle  to  melt  the  lead,  reduce  the  heat  as  quickly  as  possible, 
and  finish  the  cupellation  at  a  moderate  temperature.  Assemble 
the  beads,  part,  and  weigh.  The  weight,  multiplied  by  2,  will 
give  the  number  of  ounces  of  gold  per  ton  of  bullion. 

SILVER  AND  GOLD  IN  COPPER  BULLION  * 

Reagents.  Solution  of  mercuric  nitrate.  Dissolve  40  gms. 
Hg(NOs)2  in  1  liter  of  water. 

Solution  of  sodium  chloride.  Dissolve  19  gms.  NaCl  in  1 
liter  of  water  (1  cc.  will  precipitate  about  0.35  gm.  of  silver). 

Au  and  Ag  in  Copper-bullion.  Weigh  one  assay-ton  of  the 
drillings  which  have  been  ground  and  divided  into  coarse  and 
fine  with  a  40-mesh  sieve,  the  assay-ton  being  made  up  of  the 
coarse  and  fine  in  the  ratio  that  exists  in  the  sample  as  a  whole. 
Transfer  it  to  an  800-cc.  Jena  beaker.  Add  30  cc.  of  water  and 
10  cc.  of  the  mercuric  nitrate  solution  (  =  0.25  gm.  Hg). 

For  comparatively  pure  copper  the  amount  of  mercuric  nitrate 
may  be  reduced;  but  copper  high  in  sulphur  will  require  more  than 
10  cc.  of  the  mercuric  nitrate  solution. 

Shake  the  beaker  until  the  copper  is  amalgamated  with 
mercury.  Add  100  cc.  of  strong  sulphuric  acid,  cover  the  beaker, 
and  place  it  on  a  hot  plate. 

The  solution  appears  to  boil,  owing  to  the  reduction  of 
sulphuric  acid  and  the  evolution  of  sulphur  dioxide  gas.  This 
continues  about  an  hour. 

When  this  reaction  is  complete,  the  liquid  is  dark  green  in 
color,  and  finally  changes  to  a  light  grayish  blue.  At  this  point, 

*  Edward  Keller,  Trans.  Amer.  Inst.  Min.  Eng.,  Vol.  46,  Bull.  80,  2101. 


202  METALLURGICAL  ANALYSIS 

remove  the  beaker  and  add  450  cc.  of  water  and  a  sufficient 
amount  of  sodium  chloride  solution  to  precipitate  the  silver  and 
the  mercury  (30  cc.  will  be  sufficient  for  100  mgms.  of  silver  and 
0.25  gm.  of  mercury.  Heat  the  solution  to  the  boiling-point 
to  dissolve  copper  sulphate  and  to  coagulate  the  silver  chloride. 
Remove  the  beaker  from  the  heat  and  add  to  its  contents  150 
cc.  of  water.  Let  the  precipitate  settle  over  night,  if  convenient, 
and  filter.  Place  the  filter  with  the  precipitate  in  a  scorifier, 
sprinkle  with  litharge,  and  burn  the  paper.  Add  granulated 
lead  and  scorify.  Cupel  and  weigh  the  combined  gold  and  silver. 
Part,  and  weigh  the  gold.  (See  Fire  Assaying,  p.  224.) 

COPPER,  ARSENIC,  AND  ANTIMONY  IN  SILVER 
BULLION 

Outline.  The  bullion  is  treated  with  nitric  acid  and  the 
insoluble  residue  (Au,  Sn,  part  of  the  Sb,  a  little  Pb,  etc.) 
filtered  from  the  solution.  The  antimony  is  extracted  from 
the  residue  with  tartaric  acid  and  added  to  the  first  filtrate 
after  silver  and  lead  have  been  removed  from  it.  The  copper, 
arsenic,  and  antimony  are  then  precipitated  with  hydrogen 
sulphide.  The  arsenic  and  antimony  sulphides  are  dissolved 
in  a  solution  of  potassium  hydroxide/  the  copper  sulphide  fil- 
tered from  the  solution,  and  the  copper  determined  by  elec- 
trolysis. From  the  solution  of  arsenic  and  antimony  sulphides, 
the  arsenic  is  precipitated  and  filtered  as  magnesium  ammonium 
arsenate.  It  is  burnt  and  weighed.  The  antimony  is  measured 
in  the  filtrate  by  adding  potassium  iodide  and  titrating  with 
standard  solution  of  sodium  thiosulphate.* 

Cu  in  Bullion.  Weigh  10  gms.  of  the  bullion  and  dissolve 
it  in  50  cc.  of  dilute  nitric  acid  (1  :  4),  free  from  chlorine.  Evap- 
orate the  solution  to  25  cc.  and  add  25  cc.  of  hot  water.  Boil, 

*  Method  communicated  to  the  author  by  Oliver  C.  Martin,  Denver, 
Colo. 


COPPER,   ARSENIC,  ANTIMONY,   IN   SILVER  BULLION     203 

filter,  and  wash  by  decantation.  Reserve  this  as  Filtrate  No.  1. 
Treat  the  residue  in  the  original  beaker  with  10  cc.  of  water, 
2  cc.  of  hydrochloric  acid,  and  1  cc.  of  nitric  acid.  When  in 
solution,  filter,  and  evaporate  the  filtrate  to  dryness. 

Do  not  heat  to  a  high  temperature  when  dry,  since  that  treatment 
would  form  insoluble  lead  antimonate. 

Dissolve  the  residue  in  a  solution  of  tartaric  acid  (1  gm. 
in  10  cc.  of  water)  and  reserve  as  Solution  No.  2. 

To  Filtrate  No.  1  add  a  sufficient  quantity  of  hydrochloric 
acid  to  precipitate  the  silver  present.  Then  add  the  calculated 
quantity  of  sulphuric  acid  to  precipitate  the  lead  present.  Add 
immediately  50  cc.  of  alcohol  and  stir  vigorously. 

Lead  sulphate  is  insoluble  in  alcohol. 

Let  the  precipitate  settle,  filter,  by  suction,  wash  the  pre- 
cipitate with  a  mixture  of  alcohol  and  hydrochloric  acid  (4  :  1), 
first  by  decantation,  and  finally,  on  the  filter. 

Evaporate  the  filtrate  until  most  of  the  alcohol  has  been 
removed  and  the  volume  has  been  reduced  to  about  125  cc. 
Then  filter  into  it  the  tartaric  acid  solution  (No.  2),  and  wash 
well.  Neutralize  the  solution  with  ammonia.  Add  2  cc.  of 
hydrochloric  acid,  boil,  and  pass  H^S  through  the  solution  at  the 
boiling  temperature  for  forty-five  minutes  to  precipitate  the 
sulphides  of  copper,  arsenic,  and  antimony.  Filter  at  once  and 
wash.  Spread  the  filter  paper  on  the  inside  of  a  beaker  and 
wash  off  the  precipitate  with  as  little  water  as  possible.  Treat  the 
precipitate  with  a  solution  of  potassium  hydroxide  (2  gms.  KOH 
dissolved  in  10  cc.  of  water)  to  dissolve  the  sulphides  of  arsenic 
and  antimony.  Heat  until  the  precipitate  is  black,  and  filter. 

Dissolve  the  copper  sulphide  with  nitric  acid  and  determine 
the  copper  by  electrolysis.  (See  p.  173.) 

As  in  Bullion.  To  the  filtrate  from  the  copper  sulphide, 
obtained  according  to  the  preceding  method,  which  should  not 


204  METALLURGICAL  ANALYSIS 

measure  more  than  40  cc.,  add  1  gm.  KClOs  and  50  cc.  of  hydro- 
chloric acid.  Boil  until  the  solution  is  clear  and  the  chlorine 
is  expelled. 

The  sulphides  are  oxidized  to  sulphates. 

Cool,  neutralize  with  ammonia,  and  let  the  solution  stand -to 
permit  the  separation  of  the  small  quantity  of  lead  sulphate 
which  may  be  present.  Filter,  and  add  ammonia,  ii  quantity 
equal  to  one-third  the  volume  of  the  solution.  Add  magnesia 
mixture.  (See  p.  79.) 

K2HAs04+MgCl2+NH3+6H20=2KCl+MgNH4As04-6H20. 

Let  the  solution  stand  twenty-four  hours  or  more.  Filter 
in  a  porcelain  Gooch  crucible.  Reserve  the  filtrate  for  anti- 
mony and  burn  the  precipitate  to  convert  the  magnesium  am- 
monium arsenate  to  magnesium  pyroarsenate. 

2MgNH4As04-6H20=Mg2As207+2NH3+7H20. 

The  factor  for  As  in  Mg2As2O7  is  0.4828. 

Sb  in  Bullion.  Boil  off  the  excess  of  ammonia  from  the 
nitrate  from  the  arsenic  precipitate,  cool,  and  add  50  cc.  of 
hydrochloric  acid  and  3  gms.  of  potassium  iodide. 

SbCl6+2KI  =  2KCl+SbCl3+I2. 

Add  a  little  starch  solution  and  titrate  with  standard  solution 
of  sodium  thiosulphate. 

I2+2Na2S203  =  2NaI+Na2S406. 

For  the  method  of  making  and  standardizing  the  solution 
of  sodium  thiosulphate,  see  iodide  method  for  copper,  page  171. 
The  solution  may  be  standardized  against  copper  and  its  value 
in  antimony  determined  by  multiplying  its  value  in  copper  by 
the  factor  0.9454.  It  will  be  observed  in  the  reaction  on  page 
171,  that  2  atoms  of  copper,  in  the  form  of  copper  acetate, 


COPPER  IX  CONVERTER  COPPER  205 

liberate  2  atoms  of  iodine  from  potassium  iodide;  and  the  equa- 
tion above  indicates  that  2  atoms  of  iodine  are  liberated  by  one 
atom  of  antimony.  The  ratio  of  the  value  of  this  standard  solu- 
tion in  copper  to  its  value  in  antimony  will,  therefore,  be  equal 
to  the  ratio  of  twice  the  atomic  weight  of  copper  (2X63.57) 
to  the  atomic  weight  of  antimony  (120.2),  and  this  ratio  is 
expressed  by  the  factor  0.9454. 

COPPER  IN  CONVERTER  COPPER 

Weigh  0.5  gm.  of  the  sample  and  transfer  it  to  a  No.  4 
beaker.  Add  8  cc.  of  nitric  acid,  8  cc.  of  water,  and  1  cc.  of 
sulphuric  acid,  and  keep  the  beaker  covered  during  the  solution 
of  the  sample.  When  the  metal  is  in  solution,  boil  out  the  fumes, 
dilute  the  solution  with  water,  and  precipitate  the  copper  by 
electrolysis.  The  silver  present  is  precipitated  with  the  cop- 
per on  the  cathode  and  the  weight  of  silver,  which  has  been  pre- 
viously determined  by  the  fire  assay,  should  be  deducted  from 
the  total  weight  (291.66  ounces  =  1  per  cent).  The  silver  may 
be  removed  prior  to  the  precipitation  of  copper  by  adding  just 
enough  hydrochloric  acid  to  precipitate  it,  letting  the  chloride 
settle,  and  filtering  it  off.  The  solution  is  then  electrolyzed 
and  the  copper  weighed  directly. 

ARSENIC  AND  ANTIMONY  IN  CONVERTER  COPPER 

Outline.  The  sample  is  dissolved  in  sulphuric  and  nitric 
acids  and  most  of  the  copper  is  precipitated  from  the  solution  by 
electrolysis;  the  remaining  copper,  with  the  antimony  and  arsenic, 
is  precipitated  with  hydrogen  sulphide,  the  sulphides  of  arsenic 
and  antimony  are  extracted  with  potassium  hydroxide  solution, 
and  the  antimony  determined  by  electrolysis. 

After  the  antimony  has  been  withdrawn  from  the  solution, 
the  arsenic  is  precipitated  with  hydrogen  sulphide,  filtered  from 
the  solution,  and  dissolved  in  ammonia.  Sulphuric  acid  is 


206  METALLURGICAL  ANALYSIS 

added,  the  solution  evaporated,  diluted,  the  acid  neutralized 
with  ammonia,  hydrochloric  acid  added,  and  the  solution  fil- 
tered. An  excess  of  sodium  bicarbonate  is  added  to  the  filtrate, 
and  the  arsenic  is  titrated  with  standard  iodine  solution.* 

Reagents.  Standard  iodine  solution.  Dissolve  5.2  gms.  of 
iodine  and  9  gms.  of  potassium  iodide  in  10  cc.  of  water  and 
dilute  the  solution  to  1  liter.  Each  cubic  centimeter  should  be 
equivalent  to  about  0.0015  gm.  of  arsenic. 

To  standardize  the  solution,  dissolve  0.1  gm.  of  pure  As20s 
and  1  gm.  of  potassium  hydroxide  in  about  30  cc.  of  water. 
Acidify  the  solution  with  hydrochloric  acid,  add  sodium  bicar- 
bonate to  render  the  solution  alkaline,  and  then  add  about 

4  gms.  in  excess.     Add  a  little  starch  solution,  and  titrate  with 
the  iodine  solution.     The  factor  for  As  in  As20s  is  0.7574. 

Starch  solution.     (See  p.  111.) 

Hydrogen  sulphide,  H^S  from  a  generator. 

Potassium  hydroxide,  KOH. 

Sodium  sulphide  solution.  Dissolve  25  gms.  Na2S+9H2O 
in  100  cc.  of  water. 

Sb  in  Copper.  Weigh  10  gms.  of  the  sample  (20  gms.  if  it 
contains  less  than  5  per  cent  of  arsenic)  and  transfer  it  to  a  No. 

5  beaker.     Add  30  cc.  of  sulphuric  acid,  20  cc.  of  nitric  acid, 
and  50  cc.  of  water.     When  in  solution,  heat  to  drive  off  nitrous 
fumes,  dilute  with  water,  and  electrolyze  2.5  hours  at  4  amperes, 
using  a  cylindrical  platinum  gauze  cathode  about  75  mm.  high 
and  50  mm.  in  diameter.     The  precipitation  of  the  copper  should 
be  stopped  when  about  0.25  gm.  of  copper  remains  in  solution, 
indicated  by  a  faint  blue  color.     Remove  the  cathode,  rinsing 
back  into  the  beaker  the  adhering  solution  with  water  from  a 
jet. 

Neutralize  the  solution  with  ammonia  and  then  acidify  it 
with  3  cc.  of  hydrochloric  acid.  Pass  hydrogen  sulphide  through 
the  solution  rapidly  for  thirty  minutes  and  let  the  sulphides  of 

*E.  E.  Brownson,  Trans.  Amer.  Inst.  Min.  Eng.,  46,  Bull.  80,   1489. 


ARSENIC  AND  ANTIMONY  IN   CONVERTER  COPPER    207 

copper,  arsenic,  antimony,  etc.,  settle  thirty  minutes.  Filter 
and  discard  the  filtrate.  Wash  the  precipitate  once  on  the  paper, 
and  then  wash  the  sulphides  into  a  No.  5  beaker  with  the  smallest 
possible  amount  of  water.  Add  to  the  precipitate  in  the  beaker 
10  cc.  of  aqua  regia  and  place  the  beaker  under  the  funnel.  In 
another  beaker,  mix  5  cc.  of  water  and  20  cc.  of  aqua  regia,  heat 
to  boiling,  and  pour  through  the  filter  to  dissolve  the  small  amount 
of  sulphides  adhering  to  the  paper.  Wash  the  paper  with  a  small 
amount  of  water,  and  keep  the  bulk  of  the  solution  low  to  save 
time  in  evaporating.  Cover  the  beaker  and  boil  the  solution 
thirty  minutes.  Remove  the  cover,  and,  with  a  fine  jet  of 
water,  wash  off  the  cover  and  wash  down  the  sides  of  the  beaker. 
Evaporate  the  solution  to  dryness  at  a  temperature  low  enough 
not  to  cause  loss  by  spattering.  The  residue  should  be  heated 
until  there  is  no  longer  an  odor  of  acid. 

Add  about  5  gms.  of  potassium  hydroxide  and  30  cc.  of  water 
and  boil  vigorously  about  fifteen  minutes.  The  arsenic  and 
antimony  will  pass  into  solution.  Add  25  cc.  of  sodium  sul- 
phide solution  (25  gms.  Na2S+9H2O  in  100  cc.  of  water)  and 
boil  vigorously  about  ten  minutes.  Cool,  decant  the  clear 
solution  through  a  filter  paper  into  a  No.  2  beaker.  Again 
add  25  cc.  of  sodium  sulphide  solution  to  the  black  precipitate 
in  the  beaker,  stir  well,  and  transfer  the  precipitate  to  the  filter 
paper.  Wash  well  with  a  dilute  solution  of  sodium  sulphide 
(5  gms.  Na2S+9H2O  in  100  cc.  of  water)  from  a  wash  bottle. 

This  precipitate  may  be  washed  with  hot  water  if  care  is  taken  that 
it  be  kept  wet.  If  allowed  to  dry,  copper  will  be  oxidized  and  dis- 
solved. 

Add  to  the  filtrate,  which  should  measure  about  160  cc., 
5  cc.  of  hydrogen  peroxide  and  heat  until  the  yellow  color  of  the 
solution  fades. 

The  solution  will  become  nearly  colorless  unless  the  aqua  regia  used 
on  the  filter  paper  was  strong  enough  to  attack  it. 


208  METALLURGICAL  ANALYSIS 

Cool,  and  precipitate  the  antimony  by  electrolysis,  at  0.1 
to  0.15  ampere.  The  antimony  should  be  precipitated  in  about 
twelve  hours. 

Remove  the  cathode,  carefully  washing  off  the  solution  which 
contains  arsenic.  Then  wash  in  alcohol,  dry  carefully  over  an 
alcohol  flame,  and  weigh.  The  increase  in  weight  is  Sb. 

As  in  Copper.  Add  to  the  solution  containing  the  arsenic 
(from  which  the  antimony  has  been  precipitated)  dilute  sulphuric 
acid  (1:4)  to  distinct  acidity.  Pass  through  the  solution  a 
rapid  stream  of  hydrogen  sulphide  about  ten  minutes. 

As2(S04)3+3H2S  =3H2S04+As2S3. 

Let  the  precipitate  settle  twenty-five  minutes  and  decant 
the  solution  through  a  filter  (some  sulphur  will  run  through  the 
filter).  Transfer  the  precipitate  and  remaining  solution  directly 
to  a  No.  2  beaker.  Now  decant  again  through  the  filter  and 
place  the  beaker  containing  the  arsenic  sulphide  under  the  funnel. 
Wash  out  the  beaker  in  which  the  arsenic  was  precipitated  with 
15  cc.  of  dilute  ammonia  (1:4),  pour  this  through  the  filter  to 
dissolve  the  small  amount  of  arsenic  sulphide  which  it  contains, 
let  the  solution  run  into  the  beaker  with  the  main  precipitate, 
and  finally,  wash  with  a  little  water. 

As2S3+6NH4OH  =  2H3As03+3(NH4)2S. 

To  the  solution  of  arsenic  add  sulphuric  acid  to  neutralize 
ammonia,  and  about  8  cc.  in  excess.  Evaporate  until  the  sul- 
phuric acid  fumes  and  then  heat  the  solution  at  a  high  tem- 
perature about  1.5  hours.  Cool,  wash  down  the  sides  of  the 
beaker  with  water,  and  add  water  to  half  fill  the  beaker.  Neu- 
tralize the  acid  with  ammonia,  add  hydrochloric  acid  to  dis- 
tinct acidity,  and  filter  into  a  No.  4  beaker.  Wash  thoroughly 
with  hot  water.  Add  water  to  about  half  fill  the  beaker.  Neu- 
tralize the  acid  with  sodium  bicarbonate,  and  then  add  4  gms. 
in  excess. 


SELENIUM  AND  TELLURIUM  IN  COPPER  209 

AsCl3+3NaHC03  =  H3As03+3NaCl+3C02. 

The  solution  must  be  neutral,  but  NaOH  must  not  be  used,  since 
it  reacts  with  I. 

Cool  to  the  temperature  of  the  room,  add  starch  solution, 
and  titrate  with  standard  iodine  solution. 

H,AsO,+I,+H,0  =  H3As04+2HI. 
HI+NaHCO3  =  NaI+H20+C02. 

COPPER  IN  MATERIALS  CONTAINING  ARSENIC,  ANTIMONY, 
TELLURIUM,  AND  SELENIUM 

Weigh  0.5  gm.  of  the  sample  and  transfer  it  to  a  beaker. 
Dissolve  in  nitric  acid,  dilute  with  water,  and  add  just  enough 
hydrochloric  acid  to  precipitate  the  silver.  Filter  and  wash. 
To  the  filtrate,  add  0.1  gm.  of  iron.  When  the  iron  is  dissolved 
add  ammonia  to  precipitate  the  iron,  boil,  let  the  precipitate 
settle,  and  filter.  Dissolve  the  precipitate  in  nitric  acid,  dilute, 
and  precipitate,  as  before.  To  insure  the  separation  of  all  the 
copper,  dissolve  the  precipitate,  reprecipitate,  and  filter  a  third 
time. 

The  precipitate  of  ferric  hydroxide  carries  down  with  it  arsenic, 
antimony,  selenium,  and  tellurium,  leaving  the  copper  in  solution. 

Combine  the  filtrates  and  precipitate  the  copper  by  electrolysis 

SELENIUM  AND  TELLURIUM  IN  COPPER 

KELLER'S  METHOD* 

Se  in  Copper.  Weigh  5  to  100  gms.  of  copper,  the  quantity 
depending  upon  the  amount  of  Se  and  Te  present.  Dissolve  it 
in  nitric  acid  and  add  an  excess  of  ammonia  to  precipitate  P, 
As,  Sb,  Sn,  Bi,  Se,  Te,  and  Fe.  Filter  and  wash  the  precipitate 
with  dilute  ammonia  water  to  remove  all  the  copper. 
*  Jour.  Amer.  Chem.  Soc.,  19,  771;  and  22,  242. 


210  METALLURGICAL  ANALYSIS 

Dissolve  the  precipitate  in  hydrochloric  acid  and  saturate 
the  solution  with  hydrogen  sulphide  in  the  cold  to  precipitate 
Se,  Te,  As,  Sb,  Sn,  and  Bi  as  sulphides.  Filter  the  sulphides 
from  the  iron  and  phosphorus.  Treat  the  precipitate  with 
sodium  sulphide  and  filter.  The  filtrate  contains  all  the  Se 
and  Te  with  some  As,  Sb,  and  Sn.  Acidify  the  filtrate  with 
nitric  acid  and  evaporate  carefully  to  dryness.  Dissolve  the 
residue  in  200  cc.  of  hydrochloric  acid  (1.175  sp.gr.)  and  boil 
to  remove  nitric  acid.  Saturate  the  solution  with  sulphur  diox- 
ide and  filter  the  elementary  selenium  in  a  Gooch  crucible. 
Tellurium  is  not  precipitated  in  a  strongly  acid  solution.  Wash 
the  precipitate  with  a  mixture  of  hydrochloric  acid  (1.175) 
and  water  (9:1),  followed  by  dilute  hydrochloric  acid,  then 
by  water  to  remove  the  hydrochloric  acid,  and  finally  with 
absolute  alcohol.  Dry  at  105°  C.  and  weigh  the  selenium. 

Te  in  Copper.  Dilute  the  filtrate  from  the  selenium  with  an 
equal  volume  of  water.  Heat  it  to  boiling  and  add  sulphur 
dioxide  to  precipitate  the  tellurium.  Filter  in  a  Gooch  crucible 
and  treat  the  precipitate  of  tellurium  in  the  manner  described 
above  for  selenium. 

ANALYSIS  OF  ALLOYS 
BRASS  AND  BRONZE 

METHOD  FOR  THE  DETERMINATION  OF  SN,  PB,  Cu,  ZN, 
AL,  AND  FE 

This  is  a  rapid  method,  which  yields  only  approximately 
accurate  results.  Methods  for  the  more  accurate  separation  of 
these  metals  are  given  on  pages  215  and  220. 

Sn  in  Bronze.  Weigh  1  gm.  of  fine  drillings  for  the  sample, 
transfer  it  to  a  small  beaker,  and  add  15  cc.  of  dilute  nitric  acid 
(2:3).  Heat  to  dissolve  the  alloy  and  to  convert  the  tin  to 
metastannic  acid. 

5Sn+10HXO,  =  HwSn*Ou+5NOa+5NO. 


BRASS  AND   BRONZE  211 

Evaporate  the  solution  nearly  to  dryness.  Add  50  cc.  of 
water  and  5  cc.  of  nitric  acid  (sp.gr.  1.42).  Boil,  and  let  the 
precipitate  settle.  Filter,  and  wash  by  decantation  four  or 
five  times.  Transfer  the  precipitate  to  the  filter  and  wash  with 
boiling  water.  Dry,  separate  the  precipitate  from  the  filter 
(Fig.  31,  p.  27),  burn  the  filter  in  a  porcelain  crucible,  add  the 
precipitate,  and  ignite. 

H10Sn5Oi5  =5Sn02+5H20. 

Cool  in  a  desiccator  and  weigh.  The  factor  for  Sn  in  SnC>2 
is  0.788. 

Pb  in  Alloy.  To  the  filtrate  from  the  metastannic  acid,  add 
15  cc.  of  sulphuric  acid. 

Pb(N03)2+H2S04  =PbS04+2HN03. 

Evaporate  the  solution  nearly  to  dryness,  cool,  add  10  cc. 
of  sulphuric  acid,  and  dilute  to  50  cc.  with  water.  Filter,  wash 
with  dilute  sulphuric  acid  (1  :  10),  and  finally,  with  water. 
Dry  and  ignite  the  filter  and  residue  separately  in  a  porcelain 
crucible.  Cool  in  a  desiccator  and  weigh  PbSCU.  The  factor 
for  Pb  in  PbS04  is  0.68311. 

Cu  in  Alloy.  Boil  the  filtrate  from  the  lead  sulphate  and 
pass  a  current  of  hydrogen  sulphide  through  the  solution  for  half 
an  hour.  Filter,  and  wash  the  precipitate  with  a  solution  of 
hydrogen  sulphide  water.  Dissolve  the  copper  sulphide  on  the 
filter  with  a  little  warm,  dilute  nitric  acid,  boil  the  solution,  and 
if  sulphur  is  still  present,  filter.  To  the  solution  add  5  cc.  of 
sulphuric  acid  and  3  cc.  of  nitric  acid.  Dilute  the  solution  and 
precipitate  the  copper  by  electrolysis. 

Fe2C>3  and  A^Os  in  Alloy.  Boil  the  filtrate  from  the  copper 
sulphide  to  expel  hydrogen  sulphide.  Add  a  few  drops  of  nitric 
acid  and  boil.  Add  ammonia  until  the  solution  is  alkaline. 
Heat  to  the  boiling-point,  filter,  wash  with  hot  water,  burn, 
and  weigh  as 


212  METALLURGICAL  ANALYSIS 

Zn  in  Alloy.  Heat  the  filtrate  from  the  hydrates  of  iron  and 
aluminum  to  the  boiling-point  and  pass  through  it  a  current  of 
hydrogen  sulphide  to  precipitate  the  zinc. 

ZnS04+H2S  =  ZnS+H2S04. 

Filter,  dissolve  the  precipitate  in  about  50  cc.  of  dilute  hydro- 
chloric acid  (1  :  4),  dilute  the  solution,  and  boil  to  expel  hydrogen 
sulphide. 

ZnS+2HCl  =  ZnCl2+H2S. 

Cool,  and  add  to  the  cold  solution  a  large  excess  (50  cc.) 
of  a  10  per  cent  solution  of  sodium  ammonium  phosphate 
(NH4NaHP04+4H2O).  Add  ammonia  carefully  to  neutralize 
the  solution,  using  litmus  as  an  indicator.  Add  two  drops  of 
ammonia  in  excess  and  then  1  cc.  of  acetic  acid.  Test  with 
litmus  to  be  sure  the  solution  is  acid.  Heat  for  one  hour,  but 
do  not  boil.  After  the  precipitate  has  become  granular  and  has 
settled,  filter,  and  wash  it  with  hot  water.  Dry  the  precipitate 
and  separate  it  from  the  paper  (Fig.  31).  Dissolve  the  precipitate 
which  adheres  to  the  filter  paper  in  a  little  dilute  nitric  acid  and 
collect  the  solution  in  a  small,  weighed  porcelain  dish.  Evaporate 
the  solution  to  dryness,  add  the  dry  precipitate  which  was  sepa- 
rated from  the  paper  and  heat  gently  to  a  low  red  heat.  Cool 
in  a  desiccator  and  weigh  as  zinc  pyrophosphate  (TxizPzfy). 
The  factor  for  Zn  is  0.4289. 

Instead  of  filtering  on  filter  paper  in  the  manner  described  above 
the  zinc  ammonium  phosphate  may  be  filtered  in  a  porcelain  Gooch 
crucible,  dried  at  100°  C.  and  weighed  directly.  (See  p.  25.) 

The  zinc  may  also  be  determined  by  the  volumetric  method  de- 
scribed on  page  178.  After  the  zinc  sulphide  has  been  filtered  from 
the  solution  and  dissolved  in  50  cc.  of  hydrochloric  acid  (1  :  .4),  about 
4  gms.  of  ammonium  chloride  are  added,  the  solution  diluted  with 
250  cc.  of  hot  water,  heated  to  60°  C.  and  titrated  with  a  standard 
solution  of  potassium  ferrocyanide. 


ALLOYS  CONTAINING  TIN,   LEAD,   COPPER,  ETC.       213 

Fe  in  Alloy.  The  precipitate  formed  by  adding  ammonia 
(see  Al2Os+Fc2O3  in  alloy,  p.  211)  may  consist  of  aluminic  hydrate 
or  ferric  hydrate  or  a  mixture  of  the  two.  If  it  is  brown  in  color, 
iron  is  present.  To  determine  the  iron  in  the  alloy,  weigh  1 
gm.  of  the  sample  and  treat  it  according  to  the  process  described 
above  until  the  hydroxides  of  iron  and  aluminum  have  been 
filtered  from  the  solution.  Dissolve  the  precipitate  in  a  little 
hydrochloric  acid,  reduce  the  iron  with  a  little  stannous  chloride 
solution,  add  mercuric  chloride  solution,  and  titrate  the  iron 
with  standard  potassium  dichromate  solution;  or  the  iron  may 
be  reduced  with  zinc  in  the  presence  of  an  excess  of  sulphuric 
acid,  and  titrated  with  standard  permanganate  solution.  See 
Methods  for  iron  in  ores,  page  50  et  seq. 

Al  in  Alloy.  From  the  weight  of  Fe,  as  determined  above, 
calculate  its  value  in  Fe2Os  by  multiplying  by  the  factor  1.4298. 
Deduct  this  weight  from  the  weight  of  the  combined  oxides  of 
iron  and  aluminum,  and  multiply  the  weight  of  A12O.3  remain- 
ing by  the  factor  0.5303  to  obtain  the  weight  of  Al. 

WHITE  ALLOYS  CONTAINING  TIN,  LEAD,  COPPER, 
PHOSPHORUS  AND  ANTIMONY 

Sn  in  Alloys.  Weigh  1  gm.  of  the  sample  and  transfer  it 
to  a  small  beaker.  Add  20  cc.  of  dilute  nitric  acid  (1  :  1), 
evaporate  the  solution  nearly  to  dry  ness,  add  50  cc.  of  boiling 
water,  boil,  filter,  and  wash  the  precipitate  with  hot  2  per  cent 
solution  of  nitric  acid.  Burn  the  filter  and  precipitate  separately 
in  a  porcelain  crucible,  cool  in  a  desiccator,  and  weigh  Sn(>2. 
The  factor  for  Sn  in  SnO2  is  0.788. 

If  the  alloy  contains  phosphorus,  the  phosphorus  will  come  down 
with  the  tin,  providing  the  ratio  of  tin  to  phosphorus  is  as  great  as  8  to  1 . 
The  phosphorus  should  be  determined  (see  P  in  alloy,  p.  214)  and  its 
equivalent  in  P205  deducted  from  the  weight  of  impure  SnOa. 

Pb  in  Alloy.  To  the  filtrate  from  the  metastannic  acid, 
add  5  cc.  of  sulphuric  acid,  evaporate  the  solution  until  dense 


214  METALLURGICAL  ANALYSIS 

fumes  of  sulphuric  acid  are  evolved,  cool,  add  50  cc.  of  cold 
water,  stir,  and  let  the  precipitate  settle  half  an  hour.  Filter 
in  a  Gooch  crucible,  and  wash  with  dilute  sulphuric  acid  (1  :  9). 

Remove  the  filtrate  and  reserve  it  for  the  determination 
of  copper  and  zinc.  Then  wash  the  lead  sulphate  once  with 
alcohol.  Dry  the  precipitate  at  about  250°  C.  and  weigh  the 
PbSO4.  The  factor  for  Pb  in  PbSO4  is  0.6831. 

Cu  in  Alloy.  To  the  nitrate  from  lead  sulphate  add  1  cc.  of 
nitric  acid,  and  determine  the  copper  by  electrolysis.  (See  p.  173.) 

Zn  in  Alloy.  To  the  solution  from  which  the  copper  has 
been  precipitated  add  bromine  water,  ammonium  persulphate, 
and  ammonium  chloride.  Then  add  an  excess  of  ammonia 
and  heat  to  the  boiling-point.  If  a  precipitate  forms — Fe(OH)s, 
Mn02 — filter,  and  add  to  the  solution  an  excess  of  ammonium 
phosphate.  Heat  to  the  boiling-point  and  add  dilute  hydro- 
chloric acid  until  the  solution  is  nearly  neutral.  Boil  ten  minutes, 
filter  in  a  weighed  Gooch  crucible,  and  wash  well  with  hot  water. 
Dry  at  100°  C.  to  a  constant  weight.  The  factor  for  Zn  in 
ZnNH4PO4  is  0.3663.  For  other  methods  see  page  178. 

P  in  Alloy.  Weigh  1  gm.  of  the  alloy  and  treat  it  accord- 
ing to  the  method  described  above  for  the  determination  of 
Sn,  until  the  precipitate  of  tin  and  phosphorus  has  been  ignited 
in  a  porcelain  crucible.  Add  to  the  crucible  3  gms.  of  potassium 
cyanide,  cover,  fuse,  and  keep  at  a  dull  red  heat  for  five  minutes. 

Sn02+2KCN  =  2KCNO+Sn. 

Cool,  treat  the  fusion  with  boiling  water,  and  filter  the  tin  from 
the  solution.  Add  to  the  filtrate  20  cc.  of  strong  hydrochloric 
acid  and  boil. 

This  should  be  done  under  the  hood. 

Then  add  30  cc.  of  nitric  acid  and  evaporate  to  dryness. 
Cool,  treat  the  residue  with  nitric  acid  and  water,  filter,  and 
determine  the  phosphorus  in  the  filtrate  by  precipitating  with 


ALLOY  CONTAINING  TIN,   COPPER,  ANTIMONY,  ETC.     215 

ammonium  molybdate  solution  and  weighing  the  yellow  pre- 
cipitate.    (See  p.  75.) 

Sb  in  Alloy.     (See  p.  218.) 


ALLOY  CONTAINING  TIN,  COPPER,  ANTIMONY, 
LEAD  AND  ZINC  * 

Reagents.    Dilute  nitric  acid  (3:7). 

Sodium  carbonate, 

Sulphur,  S. 

Sodium  sulphite, 

Solution  of  hydrogen  sulphide.     Water  saturated  with 

Dilute  sulphuric  acid  (1  :  1). 

Ammonium  acetate,  NH4C2HsO2. 

Acetic  acid,  C2H402  (sp.gr.  1.04). 

Standard  ammonium  molybdate  solution,  page  175. 

Potassium  iodide,  KL 

Standard  solution  of  sodium  thiosulphate,  page  171. 

Starch  solution,  page  111. 

Solution  of  sodium  ammonium  hydrogen  phosphate. 

Dissolve  Na(NH4)HPO4-4H2O  in  water. 

Sn  in  Alloy.  Weigh  1  gm.  of  the  sample  and  transfer  it  to 
a  small  beaker.  Add  20  cc.  of  dilute  nitric  acid  (3  :  7).  Cover, 
and  when  the  sample  is  in  solution,  remove  the  cover  and 
evaporate  the  solution  to  dryness  on  a  water-bath.  Heat  in 
an  air-bath  at  120°  C.  for  an  hour.  Cool,  moisten  the  residue 
with  4  cc.  of  nitric  acid,  and  then  add  30  cc.  of  water.  Heat, 
filter,  and  wash  the  precipitate  until  the  acid  is  all  removed. 
Dry  the  precipitate  and  separate  it  from  the  paper.  Ignite 
the  paper  in  a  weighed  porcelain  crucible,  moisten  the  ash  with 
a  few  drops  of  nitric  acid,  and  ignite  gently.  Add  the  pre- 
cipitate to  the  ash  in  the  crucible  and  ignite  at  a  red  heat.  Weigh 
as  impure  Sb204-fSn02. 

*  Meade,  Chem.  Eng.,  8,  45. 


216  METALLURGICAL  ANALYSIS 

Add  to  the  crucible  a  mixture  of  dry  sodium  carbonate  and 
sulphur,  in  equal  parts,  in  quantity  about  six  times  the  weight 
of  the  oxides  in  the  crucible.  Fuse  at  a  low  temperature  until 
burning  sulphur  ceases  to  escape  between  the  crucible  and  its 
cover.  Cool,  and  dissolve  the  fusion  in  hot  water;  add  sodium 
sulphite  to  the  dark-brown-colored  solution  until  the  iron  and 
copper  sulphides  are  precipitated  and  the  solution  changes  to  a 
light  yellow  color.  Filter  off  the  iron  and  copper  sulphides,  wash 
well  with  water  containing  hydrogen  sulphide,  ignite  and  weigh 
the  residue  as  CuO  and  Fe20s.  Subtract  this  weight  from  the 
weight  of  impure  Sb2O4  and  Sn(>2  already  determined.  Dis- 
solve the  copper  and  iron  oxides  in  a  little  strong  hydrochloric 
acid,  dilute  the  solution  to  25  cc.,  add  an  excess  of  ammonia 
to  precipitate  the  ferric  hydroxide,  filter,  and  wash  with  water. 
Ignite  and  weigh  the  precipitate  as  Fe2Os.  The  factor  for  Fe 
in  Fe2O3  is  0.69939.  Acidify  the  filtrate  from  the  ferric  hydrox- 
ide with  dilute  sulphuric  acid  and  add  it  to  the  main  solution 
for  the  copper. 

Determine  the  antimony  according  to  the  method  described 
below,  calculate  its  equivalent  in  Sb204,  and  subtract  it  from 
the  combined  weight  of  Sb2O4  and  SnO2  to  give  the  weight  of 
SnO2.  The  factor  for  Sn  in  Sn02  is  0.7881. 

Pb  in  Alloy.  To  the  filtrate  from  the  antimony  and  tin, 
add  10  cc.  of  dilute  sulphuric  acid  (1  :  1)  and  evaporate  the 
solution  until  dense  white  fumes  of  sulphuric  acid  are  evolved. 
Cool,  and  dilute  the  solution.  Heat  it,  let  the  precipitate  settle, 
decant  the  clear  solution  through  a  filter,  wash  the  precipitate 
by  decantation  with  2  per  cent  sulphuric  acid,  and  then  wash 
it  with  cold  water.  Dissolve  10  gms.  of  ammonium  acetate 
in  50  cc.  of  hot  water,  and  pour  it  through  the  filter  to  dis- 
solve the  small  amount  of  lead  sulphate  deposited  on  the  paper 
by  decantation,  letting  the  solution  run  into  the  beaker  con- 
taining the  main  part  of  the  precipitate.  Wash  the  paper 
with  hot  water,  and  place  the  beaker  over  the  heat  until  the 


ALLOY  CONTAINING  TIN,   COPPER,  ANTIMONY.   ETC.     217 

lead  sulphate  is  dissolved.  Dilute  the  solution  to  200  cc., 
make  it  slightly  acid  with  acetic  acid,  and  titrate  the  lead  with 
standard  ammonium  molybdate  solution.  (See  p.  175.) 

Cu  in  Alloy.  To  the  filtrate  from  the  lead  sulphate  add 
ammonia  until  the  solution  is  faintly  alkaline,  and  then  add 
8  cc.  of  acetic  acid  and  3  gms.  of  potassium  iodide.  When  the 
potassium  iodide  is  in  solution  add  a  little  starch  solution  and 
titrate  with  standard  sodium  thiosulphate  solution.  (See  p.  171.) 

Cu  in  Alloy  Containing  Zinc.  Heat  the  filtrate  from  the 
lead  sulphate  to  boiling  and  pass  through  it  a  current  of  hydrogen 
sulphide  until  it  becomes  cold.  Filter  by  suction  and  wash 
the  precipitate  with  hydrogen  sulphide  water.  Dissolve  the 
precipitate  in  a  little  warm  dilute  nitric  acid,  evaporate  the 
solution  to  2  or  3  cc.,  dilute  slightly,  add  ammonia  until  the 
solution  is  faintly  alkaline,  and  then  add  8  cc.  of  acetic  acid, 
3  gms.  of  potassium  iodide,  and  a  little  starch  solution,  and 
titrate  with  standard  sodium  thiosulphate  solution. 

The  copper  may  also  be  determined  in  the  filtrate  from  the  lead 
sulphate  by  electrolysis. 

Zn  in  Alloy.  To  the  cold  filtrate  from  the  copper,  add  50 
cc.  of  a  10  per  cent  solution  of  sodium  ammonium  hydrogen 
phosphate.  Carefully  neutralize  the  solution  with  ammonia, 
using  litmus  paper,  and  add  2  drops  of  ammonia  in  excess. 
Acidify  the  solution  with  acetic  acid  (1  cc.  or  more  if  neces- 
sary). Heat  for  one  hour,  but  do  not  boil.  Filter  and  wash 
the  precipitate  with  hot  water,  dry,  and  transfer  it  to  a  watch 
glass.  Dissolve  the  small  amount  of  the  precipitate  on  the 
filter  in  dilute  nitric  acid  and  let  the  solution  run  into  a  small, 
weighed,  porcelain  dish.  Evaporate  the  solution  to  dryness, 
add  the  main  precipitate  from  the  watch  glass,  and  heat  gently 
at  first,  and  then  for  a  few  minutes  at  a  low  red  heat.  Cool 
and  weigh  as  Zn2?207.  The  factor  for  zinc  is  0.4289. 

The  zinc  may  also  be  determined  volumetrically  by  the  method 
described  on  page  178. 


218  METALLURGICAL  ANALYSIS 

Sb  in  Alloy.*  Weigh  1  gm.  of  the  sample,  transfer  it  to  a 
beaker,  add  1  gm.  of  potassium  iodide,  40  cc.  of  water,  40  cc.  of 
concentrated  hydrochloric  acid,  and  boil  gently  one  hour. 

The  residue  is  metallic  antimony  precipitated  from  SbCla  by  the  metals 
not  yet  dissolved.  KI  reduces  SbCl6  to  SbCla. 

Filter  on  asbestos  and  wash  five  or  six  times  with  hot  dilute 
hydrochloric  acid  (1  :  10).  Wash  the  precipitate  and  asbestos 
into  a  small  beaker  with  a  little  water  and  add  25  cc.  of  concen- 
trated hydrochloric  acid  and  a  few  crystals  of  potassium  chlorate. 
Cover  and  warm  gently,  stirring  occasionally.  When  the 
antimony  is  dissolved,  dilute  the  solution  to  100  cc.  and  filter 
out  the  asbestos,  washing  it  free  of  hydrochloric  acid.  Boil 
the  solution  vigorously  five  minutes  to  drive  off  the  chlorine. 
The  Sb  is  oxidized  to  SbCls.  Cool  to  room  temperature,  add  1 
gm.  of  potassium  iodide,  and  titrate  with  standard  sodium 
thiosulphate  solution.  (See  p.  204.) 

BISMUTH  IN  ALLOYS 

Outline.  The  alloy  is  dissolved  in  acids  and  all  the  metals 
converted  to  sulphates.  Insoluble  sulphates  are  filtered  from 
the  solution.  From  the  filtrate  bismuth  and  the  other  metals 
of  that  group  are  precipitated  with  hydrogen  sulphide.  The 
sulphides  of  copper,  arsenic,  and  antimony  are  dissolved  from 
the  precipitate  with  potassium  cyanide  solution;  the  remain- 
ing sulphides  are  dissolved  and  the  bismuth  precipitated  and 
weighed  as  the  oxychloride. 

Reagents.     Dilute  sulphuric  acid  (1  :  10). 

Hydrogen  sulphide;    H^S  from  a  generator. 

Solution  of  potassium  cyanide',  concentrated  solution  of  KCN 
in  water. 

Dilute  nitric  acid  (1:1) 

*  H.  Yockey,  Jour.  Amer.  Chem.  Soc.,  28,  646  and  1435.  Walters  and 
Apfelder,  Ibid.,  25,  635. 


BISMUTH  IN  ALLOYS  219 

Dilute  ammonia  (I  :  2). 

Dilute  hydrochloric  acid  (1  :  2). 

Bi  in  Alloy.  Weigh  1  gm.  of  the  alloy,  transfer  it  to  a  250-cc. 
Erlenmeyer  flask,  add  10  cc.  of  nitric  acid,  and  evaporate 
the  solution  until  the  residue  is  pasty,  but  do  not  let  it  boil. 
Add  7  cc.  of  hydrochloric  acid  and  heat  to  complete  the  decom- 
position of  the  alloy.  Then  add  8  cc.  of  sulphuric  acid  and 
boil  until  dense  white  fumes  of  sulphuric  acid  are  evolved. 
Cool  the  solution,  add  30  cc.  of  water,  and  boil  until  the  bismuth 
sulphate  dissolves.  Cool,  filter  quickly  before  there  is  time  for 
basic  bismuth  sulphate  to  precipitate,  and  wash  with  10  per 
cent  solution  of  sulphuric  acid.  Dilute  the  filtrate  to  100  cc. 
and  pass  a  current  of  hydrogen  sulphide  through  the  solution 
to  precipitate  bismuth,  copper,  arsenic,  and  antimony — also 
lead  if  any  remains.  Filter  and  wash  the  precipitate  with 
hydrogen  sulphide  water.  Place  the  filter  with  its  contents 
in  a  250-cc.  beaker,  add  a  concentrated  solution  of  potassium 
cyanide,  using  as  little  as  possible  to  dissolve  the  sulphides 
of  copper,  arsenic,  and  antimony.  Warm  the  solution  for  a 
few  minutes,  filter,  and  wash  the  sulphides  with  hot  water. 
Dissolve  the  sulphides  of  bismuth,  lead,  and  cadmium  by  placing 
the  filter  and  precipitate  in  a  250-cc.  beaker,  and  heating  with 
10  cc.  of  dilute  nitric  acid  (1:1).  Add  20  cc.  of  water  and 
filter  in  a  porcelain  Gooch  crucible.  Wash  the  precipitate  with 
dilute  nitric  acid.  Transfer  the  filtrate  to  a  400-cc.  beaker, 
dilute  it  to  300  cc.,  and  heat  the  solution  to  boiling.  Remove 
it  from  the  heat  and  neutralize  it  by  adding  dilute  ammonia 
(1  :  2),  testing  with  litmus  paper.  Continue  adding  ammonia, 
cautiously,  drop  by  drop,  until  the  solution  becomes  slightly 
cloudy.  Add  1  cc.  of  dilute  hydrochloric  acid  and  let  the  deter- 
mination stand  on  the  hot-plate  for  an  hour,  but  do  not  let 
it  boil.  Filter  the  bismuth  oxychloride  in  a  porcelain  Gooch 
crucible,  wash  with  hot  water,  dry  at  100°  C.,  and  weigh  as 
BiOCl.  The  factor  for  Bi  is  0.80166. 


220  METALLURGICAL  ANALYSIS 

ANALYSIS  OF  COPPER  CONTAINING  LEAD,  ANTIMONY, 
ARSENIC,  TIN,  IRON,  COBALT,  AND  NICKEL,  WHEN  ONLY 
A  SMALL  SAMPLE  OF  THE  MATERIAL  IS  AVAILABLE  * 

Reagents.     Sodium  carbonate  (Na2COs). 

Sulphur,  S. 

Hydrogen  sulphide  (£[28  from  a  generator). 

Solution  of  sodium  sulphide;  Na2$  dissolved  in  water. 

Sodium  dioxide  (Na202). 

Alcohol  (C2H60— sp.gr.  0.84). 

Tartaric  acid  (C^eOe). 

Ammonium  nitrate  (N^NOa). 

Solution  of  ammonium  nitrate.  Dissolve  10  gms.  NH4NOs  in 
1  liter  of  water. 

Ammonium  carbonate,  (NH^COs. 

Ammonium  acid  sulphide,  (NH4)HS. 

Solution  of  ammonium  sulpho-cyanate.  Dissolve  10  gms. 
NH4SCN  in  1  liter  of  water. 

Bromine  water;  water  saturated  with  Br. 

A.  Weigh  0.5  gm.  of  the  sample,  transfer  it  to  a  small  beaker, 
cover,  and  pour  down  the  lip  into  the  beaker  10  cc.  of  nitric 
acid   (sp.gr.   1.42).     Heat,   or  cool,  to  dissolve,  at  a  moderate 
rate.     Evaporate  the  solution  to  dryness  and  heat  the  residue 
at   110°   C.     Cool,   moisten  the   deposit   with  nitric   acid,   add 
50  cc.  of  water  and  then  add  ammonia  to  render  the   solution 
slightly  alkaline  and  to  precipitate  the  tin  completely.     Heat  the 
solution  to  boiling,  acidify  it  with  nitric  acid,  filter,  wash  the 
precipitate,  burn  it  in  a  porcelain  crucible,  and  weigh  it.      Re- 
serve the  nitrate  for  separate  treatment  (see  E  below). 

B.  Cover  the  residue  with  a  mixture  of  sodium  carbonate 
and  sulphur,  in  equal  parts.     Cover  the  crucible  and  fuse  until 
sulphur  has  ceased  to  be  volatilized.     Cool,  place  the  crucible 
in  a  beaker  with  water,  and  boil.     Remove  the  crucible  after 

*  F.  A.  Gooch,  Carnegie  Publication,  1,  235. 


COPPER  CONTAINING  LEAD,  ANTIMONY,  ETC.         221 

it  has  been  washed  off.  Filter  and  wash  the  residue.  If  the 
precipitate  is  large,  repeat  this  treatment.  Combine  the  nitrates 
for  treatment  under  D. 

C.  Ignite  the  precipitate — which  may  contain  sulphides  of 
lead,  copper,  and.  iron — in  a  porcelain  crucible.     Cool,  treat  the 
residue  with  aqua  regia  and  a  little  sulphuric  acid.     Evaporate 
the    solution    until    sulphuric    acid    fumes    are    evolved.     Cool, 
add  a  little  water,  filter  off  the  lead  sulphate  in  a  Gooch  cru- 
cible, dry,  and  weigh  the  PbSCU. 

To  the  nitrate  add  ammonia  to  precipitate  ferric  hydroxide. 
Boil,  filter,  burn,  and  weigh  the  Fe20s. 

Through  the  filtrate  from  the  iron  pass  a  current  of  hydrogen 
sulphide,  filter  from  the  solution  the  copper  sulphide,  burn  it 
in  a  crucible  to  CuO,  and  weigh  it. 

D.  Acidify  the  filtrate  from  B,  containing  arsenic,  antimony, 
and  tin,  with  hydrochloric  acid.     Filter,  and  reject  the  filtrate. 
Dissolve  the  precipitate  on  the  filter  with  the  smallest  amount  pos- 
sible of  warm  solution  of  sodium  sulphide.     Concentrate  the  solu- 
tion by  evaporation.     Cool  and  add  sodium  dioxide,  a  little  at  a 
time,  until  the  liquid  becomes  colorless  and  oxygen  is  liberated 
freely.     Add  to  the  solution  one-third  of  its  volume  of  alcohol 
(sp.gr.  .84).     Filter,  and  wash  with  alcohol,  gradually  increasing 
the  strength  (1  :  2),  (1  :  1),  and  then  with  (3  :  1).  The  precipitate 
should  contain  antimony  as  sodium  antimonate;  and  the  filtrate, 
sodium    arsenate   and   sodium    stannate   in   solution.     Dissolve 
the  precipitate  of  sodium  antimonate  in  a  mixture  of  dilute  hydro- 
chloric acid  (1:4)  and  5  to  10  per  cent  of  its  weight  of  tartaric 
acid.     Dilute  and  pass  through  the  solution  a  current  of  hydro- 
gen sulphide.     Filter  on  asbestos,  and  dry  in  an  atmosphere  of 
C02  at   240°   C.    (Paul's   apparatus)   and  weigh   as   antimony 
trisulphide. 

Acidulate  the  filtrate  containing  arsenic  and  tin  with  hydro- 
chloric acid.  Cool  to  0°  C.  Treat  with  twice  its  volume  of 
hydrochloric  acid  (sp.gr.  1.2)  also  cooled  to  0°  C.  Filter  out 


222  METALLURGICAL  ANALYSIS 

sodium  chloride  on  asbestos  and  pass  a  current  of  hydrogen  sul- 
phide through  the  solution  1.5  hours.  Let  the  precipitate  settle 
for  two  hours,  filter  on  asbestos,  wash  with  dilute  hydrochloric 
acid  (1:2),  and  then  with  hot  alcohol.  Dry  at  110°  C.  and 
weigh  as  As2S5. 

To  drive  off  most  of  the  acid  evaporate  the  filtrate  from 
the  arsenic  pentasulphide.  Dilute  the  solution  largely  and  pass 
through  it  a  current  of  hydrogen  sulphide.  Add  ammonium 
nitrate  to  aid  coagulation.  Filter,  and  wash  the  precipitate  with 
the  solution  of  ammonium  nitrate.  Ignite  with  ammonium  car- 
bonate and  weigh  as  SnO2- 

E.  To  the  filtrate  from  the  residue,  after  the  first  solution 
of  the  metal,  add  5  cc.  of  sulphuric  acid,  and  evaporate  until 
the  sulphuric  acid  fumes.     Dilute  to  50  cc.,  filter  on  asbestos, 
wash  with  dilute  sulphuric  acid   (1  :  3),  ignite,   and  weigh  as 
PbSCU.     Proceed  with  the  filtrate  as  follows. 

F.  To  the  filtrate  add  1  gm.  of  tartaric  acid,  nearly  neutralize 
with  ammonia,  heat  to  boiling,  and  add  5  cc.  of  dilute  sulphuric 
acid  (1  :  4),  5  cc.  of  ammonium  acid  sulphide,  and  100  cc.  of 
solution    of     ammonium     sulphocyanate.     Let    the    determina- 
tion stand  over  night,  decant  the  solution  through  asbestos  in  a 
Gooch  crucible,  and  wash  twice  by  decantation,  leaving  most 
of  the  precipitate  of  cuprous  sulphocyanate  in  the  beaker.     Re- 
serve the  filtrate  for  treatment  under  G. 

Place  the  Gooch  crucible  in  the  beaker  with  the  greater  part 
of  the  precipitate  and  dissolve  the  precipitate  in  a  mixture  of 
sulphuric  and  nitric  acids.  After  the  precipitate  has  dissolved, 
dilute  the  solution  and  filter  the  asbestos  from  it.  Evaporate 
the  solution  to  the  evolution  of  sulphuric  acid  fumes.  Dilute 
a  little  and  neutralize  with  ammonia.  Acidify  with  sulphuric 
acid,  and  precipitate  the  copper  by  electrolysis. 

G.  Boil  down  the  filtrate  from  the  cuprous  sulphocyanate 
to  one-third  its  volume,  in  order  to  remove  sulphur    dioxide; 
and  pass  through  the  hot  solution  a  current  of  hydrogen  sul- 


COPPER  CONTAINING  LEAD,  ANTIMONY,  ETC.        223 

phide  to  precipitate  antimony,  arsenic,  lead,  copper,  and 
tin,  if  present.  Filter,  and  reserve  the  filtrate  for  treatment 
under  /. 

H.  Treat  the  precipitate  obtained  above  (under  G)  on  the 
filter  with  sodium  sulphide  solution  to  dissolve  arsenic,  antimony, 
and  tin,  and  wash  the  filter.  Treat  the  filtrate  according  to  the 
methods  of  section  D.  Burn  the  filter  and  treat  the  residue 
according  to  section  C  for  lead  sulphate  and  copper  oxide. 

7.  Carefully  neutralize  the  filtrate  from  G  with  ammonia 
and  pass  through  it  a  current  of  hydrogen  sulphide  to  pre- 
cipitate iron,  nickel,  cobalt,  and  possibly  copper.  Reject  the 
filtrate.  Treat  the  precipitate  on  the  filter  with  dilute  hydro- 
chloric acid  and  wash  the  residue.  Reserve  the  filtrate  for  the 
estimation  of  iron.  Ignite  the  filter  and  residue.  Treat  the 
residue  with  aqua  regia,  evaporate  the  solution  to  dryness,  dis- 
solve the  deposit  in  hydrochloric  acid,  and  pass  through  the  solu- 
tion a  current  of  hydrogen  sulphide.  Filter  from  the  solution 
the  copper  sulphide,  ignite  it,  and  weigh  as  copper  oxide.  Care- 
fully make  the  filtrate  from  the  copper  sulphide  ammoniacal, 
pass  through  it  a  current  of  hydrogen  sulphide,  filter,  ignite, 
and  weigh  as  NiO+CoO.  If  the  precipitate  is  large,  the  nickel 
and  cobalt  should  be  separated. 

To  the  filtrate  reserved  for  the  determination  of  iron,  add 
bromine  water,  and  then  make  the  solution  alkaline  with 
ammonia,  boil  to  precipitate  the  ferric  hydroxide;  filter,  ignite, 
and  weigh  as 


224 


METALLURGICAL  ANALYSIS 


METHODS    OF   ANALYSIS    IN    THE   PRODUCTION   OF 
THE  PRECIOUS   METALS.     FIRE  ASSAYING 

ASSAY  OF  GOLD  AND  SILVER  ORES 

Sampling.  It  is  extremely  difficult  to  take  a  satisfactory 
sample  of  a  high  grade  gold  ore,  since  such  ores  usually  lack 
uniformity  in  composition  For  the  quantity  of  ore  required  for 


FIG.  81. — Two-muffle  Assay  Furnace 
Designed  for  the  Use  of  Coal. 


FIG.  82. — Assay  Furnace  for 
Liquid  or  Gaseous  Fuel. 


the  sample,  and  for  the  fineness  of  crushing  before  dividing,  see 
Richards'  table,  page  11.  The  sample  is  finally  crushed  on  a 
bucking-board  to  pass  an  80-mesh  or  a  100-mesh  screen. 

If  any  particles  of  free  gold  or  silver  in  the  ore  (metallics) 
cannot  be  crushed  to  pass  the  screen,  they  are  collected,  weighed 
and  assayed  separately  by  scorification  assay  (see  below).  The 
values  thus  found  are  properly  apportioned  to  the  whole  of  the 
sample, 


ASSAY   OF  GOLD  AND  SILVER  ORES  225 

Methods  of  Assaying.  In  the  fire  assay  for  gold  and  silver, 
the  ore  is  fused  in  a  muffle  (Figs.  81  and  82)  by  the  aid  of  fluxes 
in  the  presence  of  lead,  and  the  gold  and  silver  are  collected  by 
the  lead.  The  lead  "  button  "  is  separated  from  the  slag  and 
cupeled. 

By  cupellation,  the  lead  button  containing  the  gold  and  silver 
is  melted  on  a  bone  ash  cup  called  a  cupel  (Fig.  83),  the  lead 
is  oxidized  to  PbO,  which  is  volatilized  in  part,  and  the  re- 
mainder, and  larger  part,  is  absorbed  by  the  bone  ash,  leaving 
the  bead  of  gold  and  silver  on  the  cupel.  The  bead  is  weighed 
and  the  silver  dissolved  from  it  with  nitric  acid,  and  the  gold 
which  remains  is  weighed. 

The  gold  and  silver  may  be  absorbed  by  lead  and  separated 


FIG.  83. — Cupel.  FIG.  84. — Crucible. 

from  the  gangue  by  either  the  crucible  method,  or  the  scorifica- 
tion  method  of  assay. 

By  the  crucible  method,  the  ore  is  mixed  with  flux,  lead  oxide, 
and  a  reducing  agent,  and  melted  in  a  fire-clay  crucible.  (Fig. 
84.)  The  flux  combines  with  the  gangue  to  make  a  fusible  slag, 
at  the  same  time  liberating  the  gold  and  silver.  These  metals 
are  then  absorbed  by  the  metallic  lead,  which  has  been  reduced 
from  the  lead  oxide  by  the  reducing  agent.  When  the  fusion 
is  complete,  the  charge  is  poured  from  the  crucible  into  a  cast- 
iron  conical  mold  (Fig.  85)  and  allowed  to  cool.  The  lead  but- 
ton, which  settles  to  the  bottom,  is  separated  from  the  slag  and 
is  hammered  into  shape  (usually  a  cube)  for  the  cupel. 

By  a  scarification  assay  the  ore  is  mixed  in  a  scorifier  (Fig. 


226  METALLURGICAL  ANALYSIS 

86)  with  granulated  lead,  a  little  borax  glass  added,  and  the 
charge  is  placed  in  a  hot  muffle  and  scorified;  that  is,  the  lead 
melts,  the  ore  floats  on  its  surface,  is  roasted  and  oxidized,  the 
basic  elements  combining  with  the  borax  glass,  and  the  acid 
elements  with  the  lead  oxide,  which  form  a  slag  on  the  surface 
of  the  molten  lead.  When  the  slag  thus  formed  increases  until 
it  completely  covers  the  surface  of  the  lead,  the  charge  is  poured 
into  a  mold,  and  the  assay  finished  as  in  the  crucible  method. 

In  the  scorification  method  of  assay,  only  a  very  small 
quantity  of  ore  can  be  used.  It  is,  therefore,  not  a  satisfactory 
method  for  low-grade  ores.  Neither  is  it  satisfactory  for  basic 
ores,  owing  to  the  small  amount  of  acid  flux  that  can  be  used. 


FIG.  85. — Cast  Iron  Mold  for  Receiving  FIG.  86. — Scorifier. 

the  Fusions. 

It  is,  however,  satisfactory  for  ordinary  silver  ores,  and  for  rich 
gold  ores  and  furnace  products,  though  the  losses  are  usually 
somewhat  higher  than  in  the  crucible  method. 

The  Assay- ton.  Gold  and  silver  ores  are  usually  weighed 
in  tons  of  2000  Ibs.  avoirdupois,  and  the  value  of  the  ore  is 
expressed  in  troy  ounces  per  ton.  In  making  the  assay,  gold 
and  silver  are  weighed  in  milligrams.  To  avoid  the  necessity 
of  changing  milligrams  into  ounces  per  ton  by  calculation, 
Prof.  Chandler  devised  the  assay-ton.  The  assay-ton  is  that 
quantity  of  ore  whose  content  of  precious  metal,  weighed  in 
milligrams,  expresses  the  number  of  troy  ounces  of  precious 
metal  contained  in  a  ton  of  ore  of  2000  Ibs.  avoirdupois. 

One  ton  avoirdupois  contains  14,000,000  grains  troy;  and 
1  oz.  troy  contains  480  grains.  Therefore,  there  are  29,166  oz. 


ASSAY  OF  GOLD  AND  SILVER  ORES  227 

troy  in  1  ton  avoirdupois.  If  1  ton  contains  29,166  oz.,  1  assay- 
ton  must  contain  29,166  mgm.,  or  29.166  gms.,  that  is,  1  mgm. 
bears  the  same  relation  to  1  assay-ton  that  1  oz.  troy  does  to  1 
ton  of  2000  pounds^  avoirdupois.  The  troy  ounce  of  gold  is 
worth  $20.67. 

The  Metric  Ton.  In  those  countries  where  the  metric  system 
has  been  adopted,  ore  is  weighed  in  metric  tons  of  1000  kgms. 
each,  and  the  assay-ton  is  not  necessary.  The  sample  taken 
is  usually  10  gms.  for  the  crucible  assay,  and  every  0.01  mgm. 
of  the  metal  found  in  the  assay  equals  the  number  of  grams  per 
metric  ton.  A  gram  of  gold  is  worth  $0.66. 

Reagents.  Reducing  agents.  The  reducing  agent  combines 
with  the  oxygen  of  the  litharge  (PbO) ,  setting  free  metallic  lead 
throughout  all  parts  of  the  charge,  the  lead  falling  through  the 
molten  mass  to  the  bottom  of  the  crucible  collects  the  gold  and 
silver.  Various  carbonaceous  substances  are  used  as  reducing 
agents.  The  principal  ones  are  charcoal,  argols,  and  flour. 

2PbO+C=Pb2+C02. 

Reducing  power.  The  power  of  a  reducing  agent  must 
be  known  before  it  is  used  in  a  charge.  To  determine  the  redu- 
cing power,  weigh  1  gm.  of  the  reducing  agent  and  mix  it  in  a 
crucible  with  60  gms.  of  sodium  bicarbonate,  5  gms.  of  borax 
glass,  and  30  gms.  of  litharge;  cover  with  salt,  fuse  in  a  hot 
muffle,  pour  the  fusion  into  a  cast-iron  mold,  cool,  separate  the 
lead  button  from  the  slag,  and  weigh  it. 

In  making  up  a  charge  for  assay,  put  in  enough  reducing 
agent  to  produce  a  lead  button  that  weighs  about  18  gms. 

Oxidizing  agents.  Oxidizing  agents  are  added  to  the  assay 
to  take  sulphur  from  the  sulphides  of  the  metals  and  to  oxidize 
the  base  metals.  In  this  form  they  are  slagged  by  acid  fluxes. 
The  chief  oxidizers  are  the  nitrates  of  potassium  and  sodium. 

4ZnS+6KNO,  =4ZnO+3K,SO«+SO,+3N,. 


228  METALLURGICAL  ANALYSIS 

Desulphurizing  agents.  In  addition  to  the  nitrates  of  the 
alkalies,  iron,  alkaline  carbonates,  and  litharge  are  reagents  that 
reduce  metallic  sulphides. 

PbS+Fe=FeS+Pb. 

7PbS+4K2C03=4Pb+3(K2S.PbS)+K2S04+4C02. 
K2S-PbS+Fe=Pb+K2S-FeS. 
PbS+2PbO=3Pb+SO.. 

Fluxes.  Fluxes  are  added  to  the  charge  to  combine  with 
the  gangue  and  form  an  easily  fusible  liquid  slag,  through  which 
the  metallic  particles  can  readily  settle.  If  the  gangue  is  basic, 
the  flux  should  be  acid;  and  if  the  gangue  is  acid,  the  flux  should 
be  basic.  The  principal  basic  fluxes  are: 

Melting-point. 
Litharge  (PbO)  ............................  906°  C. 

Sodium  carbonate  (Na2C03)  .................   814°  C. 

Sodium  bicarbonate   (NaHCOs)  loses  CO2  and 

melts  at  ................................   270°  C. 

Potassium  carbonate  (K2CO3)  ................   885°  C. 

PbO+Si02=PbSi03, 

=Na2Si03+C02. 


The  principal  acid  fluxes  are: 

Melting-point. 
Silica  (SiO2)  .................  ,  ..........   1775°  C. 

Borax  glass  (Na2B4O7)  .........  "  ...........     560°  C. 

SiO,+CaCO,  =CaSiG3+C02. 

The  cover.  After  the  charge  is  mixed  in  the  crucible,  it 
is  covered  with  a  reagent  of  low  melting-point  to  catch  any 
particles  that  would  otherwise  be  thrown  out  by  the  escape  of 
gases  and  to  protect  the  charge  from  the  air.  The  agent  often 


GOLD  AND  SILVER  IN  OKE  229 

used  for  this  purpose  is  salt  (NaCl),  which  is  neutral;  but  some- 
times, however,  an  acid  cover,  borax,  is  used;  and  sometimes, 
especially  in  the  assay  of  telluride  ores,  litharge  is  used. 

Metals,  as  reagents.  In  addition  to  the  reagents  given  above, 
pure  granulated  lead  is  used  in  scorification,  pure  silver  for 
inquartation,  and  pure  sheet  lead  in  connection  with  silver  for 
inquarting  on  a  cupel. 

Purity  of  reagents.  Litharge  and  lead  usually  contain  small 
amounts  of  silver.  Tests  must  be  run  to  determine  the  amount 
of  silver  the  reagents  contain,  and  the  proper  correction  made 
for  each  assay.  It  is  also  necessary  to  test  all  the  reagents 
used  for  gold  and  silver.  This  is  done  by  making  up  a  crucible 
charge,  with  the  same  quantities  of  reagents  that  are  used  in 
the  assay  of  an  ore,  but  with  the  ore  left  out,  and  putting  it  through 
the  regular  process,  as  given  below  for  ores. 

GOLD  AND  SILVER  IN  ORE 

The  nature  of  the  charge  that  is  mixed  with  the  ore  will 
depend  upon  the  character  of  the  ore.  If  the  gangue  is  silicious, 
and  does  not  contain  reducing  agents,  such  as  sulphides  and 
arsenides,  the  charge  taken  may  be  as  follows. 

Sodium  bicarbonate 60  gm. 

Borax 5  gm. 

Litharge 30  gm. 

Ore 1  assay-ton 

Charcoal 1  gm. 

(if  another  reducing  agent  is  used,  the  quantity  taken  should 
be  sufficient  to  produce  a  lead  button  weighing  about  18  gms.). 
Place  the  ore  on  the  charge  in  a  crucible,  mix  in  the  crucible 
with  a  spatula,  and  cover  the  mixture  to  the  depth  of  half  an  inch 
with  salt.  Place  the  charged  crucible  in  a  hot  muffle,  using 
the  crucible  tongs  (Fig.  87)  and  fuse  for  about  thirty  minutes. 


230  METALLURGICAL  ANALYSIS 

When  fusion  is  complete,  withdraw  the  crucible  with  the  tongs 
(asbestos  gloves  should  be  worn  to  protect  the  hands),  shake 
the  crucible  by  giving  it  a  rotary  motion  in  a  horizontal  plane, 
and  tap  it  gently  to  settle  the  lead  in  one  mass.  Pour  the  fusion 
into  a  mold  and  let  it  freeze.  Separate  the  slag  from  the  lead 
button  and  hammer  the  lead  into  a  convenient  form  (usually  a 
cube)  for  cupellation. 

Cupellation.  Heat  the  cupel  in  a  muffle,  and  with  the  cupel 
tongs  (Fig.  88)  place  the  lead  button  on  the  hot  cupel.  Close  the 
muffle  until  the  lead  melts.  Then  reduce  the  heat  and  open  the 
muffle  so  that  the  fumes  of  lead  oxide  are  slowly  carried  from  the 
cupel.  Cupellation  should  be  carried  on  at  a  moderately  low 


FIG.  87.— Crucible  Tongs.  FIG.  88.— Types  of  Cupel  Tongs. 

temperature  to  prevent  loss  of  the  precious  metals  by  volatiliza- 
tion. The  temperature  should  be  low  enough  to  permit  the  for- 
mation of  lead  oxide  crystals,  "  feathers,"  on  the  cupel.  When 
the  lead  is  all  oxidized,  and  only  the  gold  and  silver  bead  remains, 
it  suddenly  glows,  or  "  blicks."  After  the  blick  the  cupel  is 
withdrawn  from  the  furnace. 

If  the  bead  is  large,  it  should  be  cooled  gradually  to  prevent 
"  sprouting."  This  may  be  accomplished  by  covering  the 
cupel  before  withdrawing  it  from  the  furnace  with  an  empty 
hot  cupel  or  scorifier. 

Weighing  and  Parting.  When  the  metallic  bead  is  cold, 
take  it  from  the  cupel  with  a  pair  of  strong,  pointed  pliers, 
and  carefully  brush  it  with  a  stiff  brush  to  remove  adhering 
litharge  or  bone  ash.  Then  flatten  the  bead  with  a  small  hammer 
to  break  off  any  adhering  particles  of  bone  ash,  and  weigh  it 
as  Ag+Au.  Transfer  the  weighed  bead  to  a  porcelain  crucible 


GOLD  AND  SILVER  IN  ORE  231 

(Fig.  89)  and  add  about  2  cc.  of  water  from  a  wash  bottle.     Drop 
in  nitric  acid  slowly,  until  the  bead  turns  dark  and  begins  to 
dissolve.     Stop  the  addition  of  acid  and  warm  gently.     When 
the  action  ceases,  add  more  nitric  acid,  and  heat 
the  solution  to  boiling.      Fill  the  crucible  with 
water  from  a  wash  bottle  and  carefully  empty 
it  by  pouring  the  solution  down  a  glass  rod,  leav- 
ing the  gold  behind.     The  crucible  is  then  filled 
with  water  and  emptied  in  the  same  way  a  second        lain  Annealing 
and  a  third  time  to  free  the  gold  from  all  traces        cup. 
of  silver  nitrate.     After   the   final  decantation, 
carefully  remove  the  last  drop  of  water  from  the  crucible  with 
blotting  paper  or  filter  paper  and  carefully  dry  the  crucible  over 
a  Bunsen  burner,  and  then  heat  it  until  the  black  particle  of 
gold  is  annealed  and  turns  yellow.     The  gold  is  then  transferred 
to  the  gold  balance  and  weighed.     The  difference  between  the 
weight  of  gold  and  the    combined  weight    of  gold  and  silver 
represents  the  weight  of  silver. 

In  parting  by  the  above  method  the  gold  is  sometimes  left 
in  a  powdered  condition,  especially  if  the  ratio  of  silver  to  gold 
is  high.  In  this  condition  there  is  danger  of  loss  in  washing  the 
gold  to  free  it  from  silver  nitrate. 

A  more  convenient  method  of  parting,  especially  if  many 
assays  are  to  be  made  at  the  same  time,  and  one  which  leaves 
the  gold  in  a  more  coherent  mass,  consists  in  placing  the  metallic 
bead  in  hot  dilute  nitric  acid  (1  :  9)  at  once  and  boiling  it  at  least 
fifteen  minutes.  Place  20  cc.  of  the  dilute  acid  in  each  of  the 
test-tubes  (Fig.  90);  heat  in  the  bath  until  the  acid  boils;  then 
add  the  metallic  beads  and  continue  boiling  fifteen  minutes. 
Fill  each  test-tube  with  distilled  water;  turn  an  annealing  cup 
(Fig.  91)  over  the  top  of  each  test-tube.  Invert  the  test-tube  and 
let  the  particle  of  gold  fall  into  the  annealing  cup.  Fill  up  the 
annealing  cup  with  distilled  water  from  a  wash  bottle.  Carefully 
raise  the  inverted  test-tube  to  the  top  of  the  annealing  cup, 


232 


METALLURGICAL  ANALYSIS 


letting  the  cup  fill  with  the  solution,  then  quickly  draw  the 
test-tube  to  one  side  so  that  the  remaining  solution  in  the  tube 
will  flow  into  a  receptacle  below  and  leave  the  particle  of  gold 
undisturbed  in  the  annealing  cup.  Give  the  gold  three  suc- 
cessive washings  with  warm  distilled  water.  Take  the  last 
drop  of  water  out  of  the  cup  with  clean  blotting  paper,  anneal 
the  gold  and  weigh  it. 

Inquartation.  If  the  gold-silver  bead  has  a  higher  ratio 
of  gold  to  silver  than  1  to  4,  the  silver  is  not  readily  dissolved 
from  it  with  nitric  acid.  Therefore,  when  there  is  not  four  times 


FIG.  90. — Test  Tubes  for  Parting 
Ready  for  the  Bath. 


FIG.  91.— Clay  An- 
nealing Cup. 


as  much  silver  as  gold  present,  or,  in  other  words,  if  the  total 
quantity  of  silver  present  is  less  than  four  times  the  amount 
of  gold,  a  sufficient  amount  of  silver  should  be  added  to  the  assay 
to  produce  this  ratio.  If  silver  is  to  be  determined  in  the  ore, 
as  well  as  gold,  the  additional  silver  for  inquartation  must  not 
be  introduced  until  after  the  gold-silver  bead  has  been  weighed. 
The  bead  is  then  wrapped  in  a  small  piece  of  pure  lead  foil, 
together  with  the  necessary  weight  of  pure  silver  for  inquar- 
tation, returned  to  the  muffle,  and  cupeled.*  The  bead  is  then 
parted  and  the  gold  weighed.  If  the  assay  is  for  gold  alone, 
and  it  is  known  that  there  is  not  a  sufficient  amount  of  silver  in 
the  ore  to  yield  a  button  that  will  part  readily,  the  necessary  silver 

*  The  silver  may  be  alloyed  with  the  bead  on  charcoal  before  the  blow-pipe. 


ASSAY  OF  SULPHIDE  ORE  233 

for  inquartation  may  be  added,  either  to  the  crucible,  or  to  the 
cupel,  since  the  gold  in  that  case  is  not  weighed  until  after  parting. 

ASSAY  OF  SULPHIDE  ORE 

Sulphide  ores  after  they  are  weighed  for  the  assay  may  be 
roasted  in  a  roasting  dish  in  a  muffle,  mixed  with  a  charge  similar 
to  that  given  in  the  preceding  method,  and  assayed  in  the  same 
way.  Roasting,  however,  may  be  avoided  by  making  up  a  cru- 
cible charge,  in  which  is  included  a  desulphurizing  agent.  The 
following  charge  may  be  used. 

Gms. 

Sodium  carbonate 60 

Litharge 30 

Borax 8 

Silica 2 

Place  the  flux  in  the  crucible,  add  1  assay-ton  of  ore,  and 
mix  thoroughly  with  a  spatula.  Add  three  twenty-penny  iron 
nails.  Put  the  nails  in,  points  downward,  and  press  them  well 
into  the  charge.  Add  a  half-inch  cover  of  salt  and  fuse. 

For  ores  high  in  sulphur,  reduce  the  sodium  bicarbonate 
to  50  gms.  and  increase  the  borax  to  20  gms.  and  the  silica  to  10 
gms.  For  low  sulphur  ores,  reduce  the  borax  to  5  gms.,  leave  out 
the  silica  and  iron  nails,  and  add  2  gms.  of  argols. 

After  fusing  about  twenty  minutes,  it  is  advisable  to  inspect 
the  nails  to  see  if  there  is  danger  of  their  breaking,  through 
corrosion,  at  the  surface  of  the  slag.  If  they  are  much  corroded, 
they  should  be  removed,  and  fresh  nails  added,  since  the  fusion 
cannot  be  poured  satisfactorily  if  it  includes  fragments  of  nails. 
When  the  fusion  is  complete,  withdraw  the  crucible  from  the 
muffle,  and  with  short  tongs,  take  out  the  nail,  shaking  from  them 
into  the  crucible  any  globules  of  adhering  lead.  Shake  the  crucible 
and  settle  the  lead  to  the  bottom.  Pour  the  charge  into  a  mold. 

When  cold,  separate  the  lead  from  the  slag  and  hammer 


234  METALLURGICAL  ANALYSIS 

the  lead  into  the  usual  form  for  cupellation.  If  the  lead  is  soft 
complete  the  assay  according  to  the  method  given  above  for 
silicious  ores. 

If  the  lead  is  brittle,  place  it  in  a  scorifier,  add  granulated 
lead,  and  a  pinch  of  borax  glass  and  scorify.  When  the  scorifica- 
tion  is  complete,  pour  the  contents  of  the  scorifier  into  a  mold 
and  complete  the  assay  in  the  usual  way. 

Ores  high  in  copper,  arsenic  or  antimony  should  he  done  by 
the  nitre  method.  The  charge  for  one  assay-ton  would  consist  of 
120  gms.  litharge,  35  gms.  sodium  carbonate,  10  gms.  silica,  and 
from  10  to  20  gms.  of  nitre;  the  quantity  of  nitre  depending 
upon  the  reducing  power  of  the  ore.* 

ASSAY  OF  TELLURIDE  ORE 

Charge:  Gms. 

Sodium  carbonate 25 

Potassium  carbonate .  25 

Litharge 50 

Borax  glass 14 

Flour 2J  or  more. 

(See  Reducing  Power,  p.  227.) 
Ore 0.5  assay-ton 

The  ore  is  placed  on  top  of  the  charge  and  then  thoroughly 
mixed  with  the  spatula.  Cover  with  40  gms.  of  litharge.  Place 
the  crucible  in  a  moderately  hot  muffle  and  complete  the  fusion 
at  about  1000°  C.  Pour  the  charge  into  a  mold  and  complete 
the  assay  according  to  the  method  for  silicious  ores. 

SILVER  IN  ORE 

SCORIFICATION    METHOD 

Weigh  0.1  assay-ton  and  mix  it  in  a  scorifier  with  20  gms. 
of   granulated   lead.     Cover  with   20   gms.  of   granulated  lead; 
*  C.  H.  Fulton,  "Fire  Assaying,"  pp.  61  and  115. 


ASSAY  OF  BULLION  235 

sprinkle  about  1  gm.  of  borax  glass  over  the  surface,  and  with  the 

scorifier  tongs  (Fig.  92)  place  in  a  hot  muffle,  and  scorify.     Keep 

the  door  of  the  muffle  closed  until  the  lead  is  thoroughly  melted, 

then  open  the  door  of  the  muffle  to  admit  air  for  the  oxidation 

of  the  lead,  as  well  as  of  sulphur, 

arsenic,    antimony,    etc.     When        ^.  ^- "'      -™-O 

the  slag  completely   covers  the 

lead,  the    scorification    is    com- 

plete.     The  assay  is  then  poured 

into  a  mold,  and  when  cold,  the     FIG.  92. — Types  of  Scorifier  Tongs. 

lead  is  separated  from  the  slag. 

If  the  lead  is  soft,  it  is  hammered  into    a  cube,  and  cupeled. 

If  it  is  hard  and  brittle,  it  is  rescorified  with  a  sufficient  amount 

of  granulated  lead  added  to  make  a  total  of  60  gms.     A  second 

scorification  should  slag  off  the  impurities  sufficiently  to    give 

a  soft  lead  button,  which    is  cupeled,  and    the  resulting  silver 

bead  cleaned  and  weighed  in  the  usual  manner. 

ASSAY  OF  BULLION 

Sampling.  The  bullion  is  melted  and  cast  into  bars.  Chips 
are  taken  from  diagonally  opposite  corners  of  the  bars,  the 
chips  rolled  into  fillets,  and  each  fillet  assayed  separately. 

Base  bullion  is  best  sampled  while  it  is  molten.  The  sample 
is  dipped  from  the  molten  bullion  with  a  graphite  ladle  and  poured 
slowly  into  warm  water.  The  granules  are  collected  and  as- 
sayed. 

SILVER  IN  BULLION 

FIRE  METHOD 

Silver  in  bullion  is  determined  by  cupeling  a  weighed  sample 
of  the  bullion  with  pure  lead,  weighing  the  gold-silver  bead, 
parting,  and  weighing  the  gold.  The  difference  between  the 
two  weights  represents  the  weight  of  silver. 

When  bullion  is  thus  cupeled,  considerable  quantities  of  the 


236  METALLURGICAL  ANALYSIS 

precious  metals  are  lost,  the  extent  of  the  loss  depending  upon 
the  amount  and  kind  of  base  metals  present  and  the  temperature 
at  which  the  bullion  is  cupeled.  To  make  an  accurate  assay 
of  bullion,  it  is,  therefore,  necessary  to  run  at  the  same  time  a 
check  assay  in  which  the  losses  are  determined,  from  which  the 
bullion  assay  is  corrected. 

It  is  necessary  to  make  a  preliminary  assay  of  the  bullion, 
to  determine  its  approximate  composition.  The  alloy  for  the 
check  assay  is  then  made  to  agree  with  the  approximate  com- 
position of  the  bullion.  The  quantities  of  the  precious  metals 
added  must,  of  course,  be  accurately  determined.  The  loss 
in  cupellation  is  then  determined  by  weighing  the  precious 
metals  after  cupellation. 

The  Preliminary  Assay.  Weigh  0.5  gm.  of  bullion,  wrap 
it  in  5  gms.  of  pure  lead  foil  and  cupel  carefully,  at  a  temperature 
low  enough  for  the  formation  of  "  feathers  "  on  the  cupel.  Clean, 
hammer,  and  weigh  the  bead.  Part  and  weigh  the  gold. 

The  check  assay  is  now  made  up  to  correspond  in  composi- 
tion with  the  bullion,  except  that  about  5  mgms.  more  of  silver 
are  put  in  the  check  than  were  found  in  the  bullion,  because  that 
amount  of  silver  is  usually  lost  under  these  conditions  from  such 
an  assay  in  cupellation. 

Suppose  the  weight  of  the  silver  determined  by  preliminary 
assay  on  500  mgms.,  of  the  bullion  is  478  mgms.,  and  the  gold 
2  mgms.;  there  is  a  toss  then  of  20  mgms.  (500  —  480). 

Experience  indicates  that  of  this  loss  about  5  mgms.  are 
silver  and  the  remaining  15,  probably  copper  (indicated  by 
the  color  of  the  cupel).  The  check  is  then  made  by  weighing 
very  accurately  483  mgms.  of  silver,  15  mgms.  of  pure  sheet  cop- 
per, and  2  mgms.  of  gold,  or  the  gold  bead  obtained  in  the  pre- 
liminary assay.  These  metals  are  wrapped  as  closely  as  possible 
in  pure  lead  foil  and  cupeled  in  the  muffle  with  the  bullion. 

The  weight  of  lead  foil  required  depends  upon  the  amount 
of  copper  in  the  bullion.  If  there  is  less  than  50  mgms.  of  copper 


SILVER  IN  BULLION  237 

in  500  mgms.  of  the  bullion,  add  5  grns.  of  lead  foil.  If  the 
bullion  contains  more  than  50  mgms.  of  copper  increase  the 
amount  of  lead  as  the  copper  increases;  about  5  gms.  of  lead 
for  each  50  mgms.  of  copper.  It  is  better,  however,  not  to  add 
more  than  20  gms.  of  lead  at  once.  If  the  copper  is  not  all 
removed  at  one  cupellation,  add  fresh  lead  and  cupel  again. 

Ag  in  Bullion.  After  making  the  preliminary  assay,  weigh 
two  portions  of  the  bullion,  of  500  mgms.  each,  and  make  up 
a  check  assay  in  the  manner  described  above;  wrap  each  of  the 
three  assays  closely  in  that  weight  of  lead  foil  required  for  the 
copper  in  the  bullion  as  determined  in  the  preliminary  assay. 
Place  them  in  three  hot  cupels,  arranged  in  a  line  across  the 
muffle,  the  check  assay  being  placed  between  the  duplicates  of 
the  bullion.  Close  the  muffle  until  the  charges  are  melted;  then 
open  the  muffle  and  cupel  at  a  sufficiently  low  temperature  to 
form  feathers.  When  the  beads  "  blick,"  cover  them  with 
hot  cupels  and  cool  slowly  to  prevent  sprouting.  If  a  bead 
sprouts,  it  must  be  discarded.  Clean,  hammer,  and  weigh  the 
beads.  The  loss  of  silver  in  the  check  assay  is  supposed  to 
be  sustained  in  the  same  ratio  by  the  bullion.  This  correction  is 
added  to  each  of  the  duplicate  bullion  assays  and  the  results  added. 

SILVER  IN  BULLION 
GAY-LUSSAC  METHOD  * 

Standard  Solutions.  (1)  Solution  of  silver.  Dissolve  1  gm. 
of  pure  silver  in  10  cc.  of  nitric  acid  and  dilute  the  solution 
to  1  liter.  One  cubic  centimeter  of  this  solution  will  contain 
0.001  gm.  of  silver.  The  solution  should  be  kept  in  a  green  glass 
bottle  which  is  covered  with  black  paper. 

(2)  Standard  solution  of  sodium  chloride.  Dry  NaCl  at 
125°  C.  and  weigh  5.4167  gms.  Dissolve  it  in  distilled  water  and 

*  Frederick  P.  Dewey,  Jour.  Ind.  and  Eng.  Chem.,  5,  209. 


238  METALLURGICAL  ANALYSIS 

dilute  the  solution  to  1  liter.  One  cubic  centimeter  of  this 
solution,  if  properly  prepared,  will  precipitate  0.01  gm.  of 
silver. 

(3)  Decime  salt  solution.  Measure  10  cc.  of  solution  No.  2 
and  dilute  it  to  100  cc.  If  correct,  1  cc.  of  this  solution  will 
precipitate  0.001  gm.  of  silver. 

Care  should  be  taken  that  the  temperature  of  these  solu- 
tions is  the  same  when  they  are  prepared. 

The  sodium  chloride  solution  (No.  2),  is  standardized  as 
follows.  Weigh  1  gm.  of  pure  silver,  dissolve  it  in  10  cc.  of  nitric 
acid,  dilute  the  solution  to  about  80  cc.,  add  100  cc.  (measured 
with  a  pipette)  of  No.  2  solution,  agitate  violently,  and  let  the 
silver  chloride  settle.  Then  add  1  cc.  of  the  decime  solution. 
If  a  precipitate  appears,  shake  vigorously,  let  the  precipitate 
settle  and  add  another  cubic  centimeter.  Shake  and  let  the 
precipitate  settle,  and  continue  adding  this  solution,  1  cc.  at 
a  time,  until  no  precipitate  is  produced.  Then  add  1  cc.  of  the 
silver  solution  (No.  1  above),  and  continue  adding  1  cc.  at  a 
time  until  no  precipitate  forms.  Suppose  100  cc.  of  the  strong 
solution  of  sodium  chloride  are  run  in;  then  7  cc.  of  the  decime 
solution  are  added  before  a  precipitate  ceases  to  form.  Now, 
if  on  adding  the  solution  of  silver,  1  cc.  at  a  time,  the  first 
produces  a  precipitate  and  the  second  does  not,  1  gm.  of  silver 
would  be  equivalent  to  100.6  cc.  of  No.  2  solution. 

The  solution  is  corrected  as  follows:  100  cc.  of  the  sodium 
chloride  solution  should  contain  0.54167  gm.  of  salt;  but  it 
requires  100.6  cc.  of  the  solution  to  contain  that  amount.  There- 
fore, 100  cc.  contains  ~—  -  =0.53844;  that  is,  0.00323 

100  6 

gm.  (0.54167-0.53844)  per  100  cc.  should  be  added. 

If  the  solution  is  too  strong,  it  may  be  corrected  accord- 
ing to  the  method  in  the  following  example.  Suppose  after 
adding  100  cc.  of  No.  2  solution  and  1  cc.  of  the  decime  solu- 
tion we  titrate  back  with  8  cc.  of  the  silver  solution;  then 


SILVER  IN  BULLION  239 

99.4  cc.  [100.1 -(0.8-0.1)]  would  contain  0.54167  gm.  NaCl; 
and  that  is  the  amount  of  NaCl  which  should  be  contained  in 
every  100  cc.  Therefore,  add  0.6  cc.  (100-99.4)  for  every  99.4 
cc.  of  solution  left. 

After  correcting  the  solution  No.  2,  make  another  decime 
solution  from  it,  test  again  and  correct,  if  necessary,  until  it  is 
exactly  right. 

Ag  in  Bullion.  Make  a  preliminary  test  as  follows:  Weigh 
0.5  gm.  of  bullion,  dissolve  it  in  dilute  nitric  acid,  and  titrate 
first  with  the  standard  sodium  chloride  solution,  and  finally 
with  the  decime  solution.  When  the  approximate  fineness  is 
determined,  weigh  that  quantity  of  bullion  which  contains  1 
gm.  of  silver,  dissolve  it  in  a  250-cc.  flask  in  dilute  nitric  acid,  and 
dilute  with  water  to  80  cc.  Add  100  cc.  of  the  standard  sodium 
chloride  solution,  shake  vigorously,  and  let  the  precipitate  settle 
Add  decime  sodium  chloride  solution,  1  cc.  at  a  time,  until  no 
precipitate  forms,  shaking  after  each  addition.  Then  add 
standard  silver  solution  in  the  same  way  until  a  precipitate 
ceases  to  form. 

Example.  Suppose  we  weigh  and  dissolve  1.02  gms.  of  bul- 
lion and  add  100  cc.  of  standard  sodium  chloride  solution  and 
9.5  cc.  of  decime  solution,  and  then  titrate  back  with  3  cc.  of 
standard  silver  solution,  the  third  producing  no  precipitate. 

The  result  is  calculated  as  follows: 

Mgms.  silver. 

100  cc.  standard  salt  solution  are  equivalent  to. .    1000 
9.5  cc.  decime  salt  solution  are  equivalent  to. .         9.5 


Less  2  cc.  standard  silver  solution. 


1007.5 
1.02  gms.  of  bullion  then  contain  1.0075  gms.  of  silver.     One 


240  METALLURGICAL  ANALYSIS 

gram  of  the  bullion  contains  (  -• )  .9878  gm.   of  silver,  and 

1000  gms.  of  the  bullion  would  contain  987.8  gms.  of  silver.     The 
bullion  is,  therefore,  987.8  fine. 

GOLD  IN  BULLION 

Make  a  preliminary  assay  of  the  bullion  to  determine  its 
approximate  composition  and  make  a  check  assay  in  a  muffle 
similar  to  that  described  for  preliminary  assay  of  silver  bullion 
(see  p.  236).  Weigh  0.5  gm.  of  the  bullion  and  add  enough  pure 
silver  to  make  the  ratio  of  silver  to  gold  2  to  1;  an  experienced 
assayer  can  estimate  this  from  the  color  of  the  bullion.  Wrap 
the  bullion  and  silver  in  about  8  gms.  of  pure  lead  foil  and  cupel, 
clean  the  button,  and  weigh.  Part  and  weigh  the  gold. 

Suppose,  for  example,  that  from  0.5  gm.  of  bullion  we  obtain 
380  mgms.  of  gold  and  15  mgms.  of  silver.  Since  experience 
indicates  that  0.3  mgm.*  of  gold  is  lost  in  the  cupellation  of  500 
mgms.,  395.3  mgms.  of  the  bullion  are  made  up  of  gold  and 
silver,  leaving  104.7  mgms.  for  base  metal — probably  copper. 

To  make  the  check  assay,  weigh  380.3  mgms.  of  pure  gold, 
760.6  mgms.  of  silver  (380.3  X2),  and  104.7  mgms.  of  pure  copper. 
Wrap  in  10  gms.  of  lead  and  cupel  with  the  bullion. 

Au  in  Bullion.  Weigh  500  mgms.  of  the  bullion  in  duplicate. 
Add  enough  silver  to  make  the  ratio  of  silver  to  gold  2  to  1, 
as  determined  by  the  preliminary  assay.  [(380.3  X2)  — 15  =  745.6]. 
Wrap  in  lead  foil,  the  weight  of  lead  taken  depending  upon  the 
amount  of  base  metal  in  the  bullion.  For  the  quantity  required, 
see  assay  of  silver  bullion  (p.  236)  Place  the  duplicate  assay 
with  the  check  in  hot  cupels  in  the  muffle  and  cupel  according 
to  the  method  described  for  the  fire  assay  of  silver. 

T.  K.  Rose  f  has  found  that  the  losses  of  gold  are  slightly 

*  Rose,  "  Metallurgical  of  Gold,"  p.  448. 
t  Eng.  and  Min.  Jour.,  80,  492. 


GOLD  AND  SILVER  IN  LEAD  BULLION  241 

greater  from  the  cupels  next  to  the  sides  of  the  muffle  than  from 
those  in  the  center,  and  recommends  that  the  check  assays  be 
distributed  throughout  the  muffle. 

After  cupeling,  each  button  is  cleaned,  hammered,  annealed, 
rolled  into  a  thin  sheet,  and  then  coiled  into  a  "  cornet."  The 
cornets  are  parted,  annealed,  and  weighed,  and  the  weight  of 
the  gold  found  in  the  bullion  corrected  from  the  loss  or  gain  in 
weight  of  the  gold  in  the  check  assay. 

The  results  are  reported  as  parts  of  gold  in  1000  parts  of  the 
bullion.  Bullion,  for  instance,  which  contains  984.6  parts 
gold  in  1000  parts  of  the  bullion  is  said  to  be  984.6  fine. 

GOLD  AND  SILVER  IN  LEAD  BULLION 

Weigh  four  portions  of  the  bullion,  0.5  assay- ton  each,  and 
mix  each  portion  with  30  gms.  of  granulated  lead  in  a  scorifier. 
Add  1.5  gms.  of  borax  glass  and  0.5  gm.  of  silica  and  scorify.  (See 
p.  234.) 

Separate  the  slag  from  the  button  and  save  it.  Cupel  the 
lead  button  and  assay  the  scorifier  slag  and  the  cupel  in  a  crucible, 
using  the  following  charge:  15  gms.  of  sodium  carbonate,  45  gms. 
of  borax  glass,  80  gms.  of  litharge,  and  2  gms.  of  argols.  Mix 
and  cover  with  a  little  litharge.  Complete  the  assay  in  the  usual 
way  and  correct  the  original  assay  accordingly. 

If  the  bullion  is  free  from  copper,  arsenic,  antimony,  zinc, 
sulphur,  etc.,  it  may  be  cupeled  without  scorification  as  follows: 
Weigh  0.5  assay-ton  and  wrap  it  in  about  8  gms.  of  sheet  lead  and 
cupel.  To  correct  the  assay,  the  cupels  are  crushed  and  assayed 
by  the  crucible  method,  using  the  charge  given  above.  The 
weights  of  the  precious  metals  obtained  in  the  correction  assay 
are  added  to  the  weights  obtained  by  the  original  assay. 


242  METALLURGICAL  ANALYSIS 


GOLD  AND  SILVER  IN  CYANIDE  SOLUTIONS 

Measure  300  cc.  of  the  solution  and  transfer  it  to  a  porcelain 
evaporating  dish.  Sprinkle  40  gms.  of  litharge  over  the  surface 
of  the  solution.  Evaporate  the  solution,  without  boiling,  to  dry- 
ness.  When  dry,  scrape  out  the  residue  with  a  spatula  and  mix 
it  in  a  fire-clay  crucible  with  the  following  charge: 

Gms. 

Sodium  carbonate 30 

Borax  glass 10 

Silica 20 

Charcoal 1 

If  any  of  the  residue  sticks  to  the  dish,  wipe  it  out  with  a  moist- 
ened piece  of  filter  paper  and  add  it  to  the  charge  in  the  crucible. 
Cover  the  charge  with  litharge,  fuse  it  in  a  muffle,  and  complete 
the  assay  in  the  usual  way  (See  p.  229.) 

PREPARATION  OF  PURE  SILVER 

Dissolve  pure  silver  foil  in  nitric  acid.  Filter,  dilute  the 
nitrate,  and  precipitate  the  silver  with  hydrochloric  acid.  Filter 
and  wash  the  silver  chloride  with  dilute  hydrochloric  acid.  Trans- 
fer the  silver  chloride  to  a  beaker,  and  add  pure  sheet  aluminum 
and  hydrochloric  acid.  When  the  silver  has  been  precipitated 
as  metallic  silver,  and  the  aluminum  is  all  dissolved,  wash  by 
decantation,  dry,  and  fuse  the  silver  in  a  cupel.  The  melting- 
point  of  silver  is  960°  C.* 

PREPARATION  OF  PURE  GOLD 

Dissolve  the  purest  gold  obtainable  (cornets)  in  aqua  regia. 
Dilute  and  let  the  solution  stand  several  days  to  allow  the  silver 
chloride  to  settle.     Siphon  off  the  clear  solution  and  evaporate 
*  Day  and  Sosman,  1910. 


FREE  CYANIDE  IN  CYANIDE  SOLUTIONS  243 

it  nearly  to  dryness.  Dilute  the  solution  largely  with  distilled 
water,  add  a  little  sodium  bromide  dissolved  in  water,  and  let 
the  solution  stand  several  days.  Again  siphon  off  the  clear 
solution  and  precipitate  the  gold  on  aluminum  by  letting  the 
solution  drop  slowly  from  a  burette  into  a  beaker  containing 
pure  aluminum  foil.  When  the  gold  is  precipitated,  add  hydro- 
chloric acid  to  dissolve  the  aluminum.  Decant,  and  wash  the 
gold  by  decantation.  Dry,  and  melt  it  into  a  bead  in  a  cupel. 
The  melting-point  of  gold  is  1062°  C.* 

TESTING   CYANIDE   SOLUTIONS 
FREE  CYANIDE  IN  CYANIDE  SOLUTIONS 

Reagents.  Standard  solution  of  silver  nitrate.  Dissolve 
13.04  gms.  AgNOs  in  water  and  dilute^  the  solution  to  1  liter. 
One  cubic  centimeter  of  this  solution  is  equivalent  to  0.004  gm. 
CN  or  0.01  gm.  KCN. 

Solution  of  potassium  iodide.  Dissolve  10  gms.  KI  in  a 
liter  of  water. 

FREE  CYANIDE 

Measure  10  cc.  of  the  cyanide  solution  with  a  pipette  (if 
the  solution  is  weak,  take  50  cc.),  and  transfer  it  to  a  beaker. 
Add  about  8  cc.  of  potassium  iodide  solution  as  an  indicator 
and  titrate  with  standard  silver  nitrate  solution  until  a  yellow 
tinge  is  given  to  the  solution  by  silver  iodide. 

AgN03+KCN  =AgCN+KN03. 
AgCN+KCN  =KAg(CN)2. 
AgN03+KI  =AgI+KNO3. 

If   10   cc.   of  the  cyanide  solution  are  tested,   every  cubic 
centimeter  of  the  standard  silver  nitrate  solution  used  will  repre- 
*  Day  and  Sosman,  1910. 


244  METALLURGICAL  ANALYSIS 

sent  0.04  per  cent  CN,  or  0.1  per  cent  KCN,  which  is  equivalent 
to  1  kilogram  KCN  per  metric  ton  of  1000  kg.  or  2  Ibs.  per  ton 
avoir.  If  50  cc.  are  titrated  every  cubic  centimeter  of  the 
standard  solution  will  represent  0.008  per  cent  CN  or  0.02  per 
cent  KCN. 

When  gold  is  dissolved  in  a  solution  of  an  alkaline  cyanide,  the 
double  cyanide  of  the  alkali  and  gold  is  formed.  A  given  weight  of 
cyanogen,  then,  whether  combined  with  sodium  or  potassium,  should 
always  dissolve  the  same  amount  of  gold,  other  conditions  being  the 
same,  and,  owing  to  the  fact  that  sodium  has  a  smaller  atomic  weight 
than  potassium,  a  smaller  quantity  of  sodium  cyanide  than  of  potassium 
cyanide  will  be  required  to  dissolve  a  given  weight  of  gold. 

In  the  method  above,  it  is  the  quantity  of  cyanogen  only  that  is 
measured  by  titration,  but  its  equivalent  in  potassium  cyanide  is  usually 
reported.  This  is  due  to  the  fact  that  potassium  cyanide  was  the  only 
cyanide  available  when  the  cyanide  process  was  developed.  Now  that 
sodium  cyanide  is  much  used  for  this  purpose,  it  is  not  accurate  to 
report  as  potassium  cyanide  the  equivalent  of  the  cyanogen  found. 

From  the  molecular  weights  KCN  (65.11),  NaCN  (49.01),  and 
CN  (26.01),  we  find  that  the  percentage  of  CN  in  pure  KCN  is  40,  and 
in  NaCN  it  is  53. 

If  40  per  cent  of  cyanogen  is  found  in  cyanide,  it  is  not  correct  to 
assume  that  the  material  is  pure  KCN  (100  per  cent);  for,  if  the  cyan- 
ide were  NaCN,  it  would  only  have  to  be  75.5  per  cent  pure  to  yield 
that  amount  of  CN.  The  remainder  might  consist  of  any  adulterant 
wholly  free  from  cyanogen.  It  is  to  be  regretted  that  the  cyanide  proc- 
ess is  not  conducted  on  the  basis  of  the  active  cyanogen  present,  instead 
of  its  equivalent  in  potassium  cyanide. 

TOTAL  CYANIDE 

Total  cyanide  has  been  denned  as  "  the  equivalent,  in  terms 
of  potassium  cyanide,  of  all  the  cyanogen  existing  as  simple 
cyanides  and  easily  decomposable  double  cyanides,  such  as 
K2Zn(CN)4."  *  It  might  be  termed  available  cyanogen,  since 
it  is  the  cyanogen  existing  as  a  simple  cyanide  after  the  addition 
of  an  excess  of  sodium  hydroxide. 

*  Clennell,  "  The  Cyanide  Handbook,"  440. 


PROTECTIVE  ALKALI  IN  MILL  SOLUTIONS  245 

Reagents.     Standard  silver  nitrate  solution.     (See  p.  243.) 
Alkali?ie  indicator:    Take    100   cc.   of  the  potassium  iodide 
solution  (p.  243)  and  add  to  it  4  gms.  NaOH. 

Total  Cyanide.  Measure  50  cc.  of  the  solution  to  be  tested, 
add  to  it  10  cc.  of  the  alkaline  indicator  solution,  and  titrate  with 
the  standard  silver  nitrate  solution  to  a  faint  yellow  turbidity. 

Na2Zn(CN)4+2NaOH  =4NaCN+Zn(OH)2. 
Also  see  reactions  on  page  243. 

PROTECTIVE  ALKALI  IN  MILL  SOLUTIONS 

Reagents.  Standard  acid.  Nitric,  hydrochloric,  sulphuric, 
or  oxalic,  acid  may  be  used,  and  it  is  convenient  to  make  the 
solution  equivalent  to  0.001  gm.  of  the  alkali  per  cubic  centimeter. 

If  nitric  acid  is  used,  a  solution  containing  2.257  gms.  HNOa 
(sp.gr.  1.42)  per  liter,  will  be  equivalent  per  cubic  centimeter 
to  about  0.001  gm.  of  NaOH,  or,  a  solution  of  the  same  strength 
is  made  if  1  cc.  of  nitric  acid  (sp.gr.  1.42)  be  added  to  625  cc. 
of  water. 

NaOH+HNOs  =NaN03+H20. 

Nitric  acid  (sp.gr.  1.42)  contains  69.77  per  cent  of  HNOs 
by  weight. 

If  oxalic  acid  is  used,  1.5753  gms.  of  crystallized  H2C204+ 2H20 
per  liter  will  give  a  solution  of  the  same  strength;  that  is,  1  cc. 
will  be  equivalent  to  0.001  gm.  NaOH. 

2NaOH+H2C204  •  2H2O  =  Na2C204+4H20. 

Phenolphthalein  solution:  1  gm.  C2oHi404  dissolved  in  500  cc. 
alcohol  (95  per  cent  C2HeO) . 

Silver  nitrate  solution.     (See  p.  243.) 

Alkali.  Measure  with  a  pipette  a  convenient  volume  of 
the  solution  to  be  tested  (50  cc.)  and,  if  it  contains  no  zinc, 


246  METALLURGICAL  ANALYSIS 

add  to  it  a  solution  of  silver  nitrate  until  a  slight  permanent 
turbidity  is  produced. 

2KCN+AgN03  =  KN03+KAg(CN)2. 

If  the  simple  cyanides  were  not  broken  up,  they,  as  well  as  the  free 
alkali,  would  react  with  the  standard  acid  in  titration. 

Add  3  drops  of  phenolphthalein  solution  and  titrate  with 
standard  acid  until  the  pink  color  disappears      (See  p.  84.) 


PROTECTIVE  ALKALI  IN  THE  PRESENCE  OF  ZINC 

Reagents.  Potassium  ferrocyanide  solution.  Dissolve  5  gms. 
K4Fe(CN)e  in  100  cc.  of  water.  For  other  reagents  see  the 
preceding  method. 

Alkali.  Measure  with  a  pipette  50  cc.  of  the  solution  to  be 
tested,  add  10  cc.  (an  excess)  of  potassium  ferrocyanide  solution. 

If  the  solution  contains  zinc  as  well  as  an  alkali,  when  silver  nitrate 
is  added  the  hydroxide  is  precipitated,  according  to  Clennell,*  in  the 
following  way. 

K2Zn(CN)4+2KOH+2AgN03=Zn(OH)2+2KAg(CN)2-f2KN03. 
The  potassium  ferrocyanide  is  added  to  liberate  the  alkali. 
2Zn(OH)2+K4Fe(CN)6=Zn2Fe(CN)6+4KOH. 

Proceed  according  to  the  method  above  (p.  245)  by  adding 
silver  nitrate  to  a  slight  turbidity  and  titrating  with  standard 
acid  after  the  addition  of  phenolphthalein  solution. 

ACIDITY  OF  ORE 

Reagents.    Standard  acid.     (See  p.  245.) 
Standard  alkali:    a  solution  of  sodium  or  calcium  hydroxide 
equivalent  to  the  standard  acid. 

Phenolphthalein  solution.     (See  p.  245.) 

*  "  The  Cyanide  Hand  Book,"  439. 


CYANOGEN  IN  COMMERCIAL  CYANIDE  247 

Weigh  200  gms.  of  ore,  transfer  it  to  a  suitable  bottle  for 
agitation,  add  400  cc.  of  the  standard  alkali  solution  and  agitate 
one  hour.  Filter  100  cc.  of  this  solution  from  the  bottle,  add 
to  it  two  drops  of  phenolphthalein  solution,  and  titrate  with 
standard  acid. 

If  the  standard  acid  and  alkali  solutions  are  exactly  equal 
in  value,  deduct  the  number  of  cubic  centimeters  of  standard 
acid  used  in  the  titration  from  100,  and  multiply  the  remainder 
by  4,  since  400  cc.  were  used.  The  result,  multiplied  by  0.001, 
will  give  the  acidity  of  200  gms.  of  ore,  or  the  weight  in  grams  of 
the  alkali  required  to  neutralize  the  acid  in  200  gms.  of  ore.  This 
quantity  multiplied  by  5  will  give  the  weight  of  the  alkali  in 
kilograms,  required  for  a  metric  ton  of  the  ore;  or  multiplied 
by  10,  will  give  the  number  of  pounds  required  for  one  ton 
avoirdupois. 

CYANOGEN  IN  COMMERCIAL  CYANIDE 

Sampling.  When  a  case  of  cyanide  is  opened,  break  off 
and  select  from  many  places  small  lumps  of  the  cyanide  to  a 
weight  of  about  200  gms.  Grind  it  quickly  in  a  porcelain  mortar, 
taking  great  care  not  to  inhale  the  dust.  It  is  well  to  grind  it 
in  a  hood  which  is  provided  with  a  strong  exhaust.  Mix  the 
powder  and  transfer  a  few  grams  for  analysis  to  a  well-stoppered 
bottle. 

Reagent.     Standard  silver  nitrate  solution.     (See  p.  243.) 

CN  in  Commercial  Cyanide.  Weigh  from  a  weighing  bottle 
about  0.5  gm.  of  the  cyanide,  transferring  it  directly  from  the 
weighing  bottle  to  a  quarter-liter  Erlenmeyer  flask.  Add  100 
cc.  of  water  to  dissolve  the  cyanide.  Add  5  cc.  of  potassium 
iodide  solution  and  titrate  with  standard  silver  nitrate  solution. 

The  result  may  be  reported  in  CN  or  in  its  equivalent  of 
KCN  or  NaCN.  (See  free  cyanide  in  mill  solutions,  p.  243.) 

If  the   cyanide   contains  soluble  sulphides,   before  titrating 


248  METALLURGICAL  ANALYSIS 

with  silver  nitrate  solution,  agitate  the  cyanide  solution  with 
a  little  alkaline  solution  of  lead  acetate  and  filter,  to  prevent 
the  darkening  of  the  solution  while  titration  goes  on. 

WEIGHT  OF  ORE  IN  SLIME 

The  percentage  of  ore  in  mill  pulp  may  be  conveniently 
estimated  at  any  time  by  weighing  a  flask  or  bottle  filled  with 
the  pulp  and  calculating  the  percentage  in  the  manner  given 
below,  by  the  use  of  the  following  data,  previously  determined, 
once  for  all: 

Weight  of  the  bottle  empty  .........  =b 

Weight  of  the  bottle  filled  with  water  =5 

Determine  the  specific  gravity  of  the  dry  slime  as  follows: 
Dry  a  quantity  of  the  slime  and  weigh  200  gms.  or  any 
convenient  quantity  (S).  Boil  it  in  a  small  quantity  of  water 
to  liberate  entangled  air,  cool  and  wash  it  into  the  empty  bottle. 
Add  water  to  fill  the  bottle,  and  weigh.  Let  the  weight 
equal  C.  The  specific  gravity  (G)  is  calculated  from  the  equa- 


Then  to  find  the  percentage  of  ore  in  pulp,  fill  the  bottle 
with    the    pulp    and    weigh    it.     Let    the    weight  =  £'.      Then 

lOOQS'  -ff)G 

—  -  —        —  —  equals  the  percentage  of  ore  in  the  pulp. 
(Or—  1)(&  —o) 


THE  PLATINUM   METALS  249 

THE  PLATINUM  METALS 

PLATINUM 
DEWEY'S  METHOD* 

Weigh  one  assay-ton  of  the  material  (or  0.5  assay-ton  if 
much  platinum  is  present)  and  treat  it  according  to  the 
method  for  the  assay  of  gold  ore,  page  229,  until  the  metallic 
bead  has  been  parted  with  nitric  acid. 

If  only  a  small  quantity  of  platinum  is  present,  it  will  be  dissolved 
with  the  silver.  If  there  is  much  platinum  present,  some  will  remain 
with  the  gold;  in  this  case,  the  residue  is  annealed,  inquarted  and  parted 
again,  and  perhaps  a  third  time  to  insure  the  complete  separation  of  the 
platinum. 

If  the  nitric  acid  solution  containing  the  silver  and  platinum 
is  strongly  acid,  dilute  it.  It  may  be  evaporated  to  a  small 
bulk  before  dilution  if  the  volume  is  large. 

Now  add  slowly  to  the  diluted  nitric  acid  solution  containing 
the  silver  and  platinum,  while  stirring,  15  cc.  hydrogen  sulphide 
solution,  made  by  diluting  1  cc.  of  concentrated  hydrogen  sul- 
phide water  to  15  cc. 

The  hydrogen  sulphide  precipitates  all  the  platinum,  if  the  amount 
is  small,  and  enough  silver  to  produce  a  bead  of  suitable  size. 

If  much  platinum  is  present,  it  will  be  necessary  to  add  2  cc.  of 
strong  hydrogen  sulphide  water,  diluted  to  30  cc. 

Stir  occasionally  and  let  the  precipitate  collect  three  to  four 
hours  or  over  night,  if  convenient.  Filter  and  reserve  the  filtrate 
for  a  second  precipitation  of  platinum  if  the  quantity  of  the 
metal  should  be  large.  Dry  the  filter  in  a  porcelain  crucible 
and  burn  at  a  low  heat.  Wrap  the  metallic  sponge  in  a  thin 
sheet  of  lead  foil  and  cupel.  Part  the  bead  in  strong  sulphuric 

*  Trans.  Amer.  Inst.  Min.  Eng.,  43,  578. 


250  METALLURGICAL  ANALYSIS 

acid.     If  necessary,  boil  a  second  time  in  strong  sulphuric  acid, 
wash  by  decant ation,  anneal  and  weigh. 

If  there  is  doubt  as  to  the  identity  of  the  metal,  it  may  be  dissolved 
in  aqua  regia  and  qualitative  tests  applied.  See  page  319. 

PLATINUM  * 

Weigh  1  gm.  of  the  sample  and  treat  it  in  a  250  cc. 
Jena  beaker  with  10  cc.  of  nitric  acid,  10  cc.  of  hydrochloric 
acid,  and  5  cc.  of  water  in  a  water-bath  until  action  ceases; 
then  boil  on  the  hot  plate  with  repeated  additions  of  hydro- 
chloric acid  until  all  the  nitric  acid  is  expelled.  Evaporate 
the  solution  to  40  cc.,  dilute  to  100  cc.  with  water  and  filter. 
Evaporate  the  nitrate  to  40  cc.,  add  25  cc.  of  ethyl  alcohol  and 
25  cc.  of  saturated  solution  of  ammonium  chloride.  Stir  well, 
heat  to  boiling,  and  let  the  precipitate  settle  over  night  in  a  cool 
place.  Filter  (NH^PtCle  in  a  weighed  Gooch  crucible,  wash 
with  a  20  per  cent  solution  of  ammonium  chloride,  dry,  ignite, 
and  weigh  as  Pt. 

If  the  material  is  low  in  platinum,  begin  with  8  or  10  deter- 
minations of  1  gm.  each  and  combine  them  at  the  end  to  obtain 
a  convenient  quantity  to  weigh. 

The  precipitate  of  (NH4)2PtCl6  should  be  ignited  very  carefully  to 
prevent  loss  of  Pt  mechanically  by  the  sudden  expulsion  of  gas.f 

PALLADIUM  t 

Weigh  0.5  gm.  of  the  material  and  transfer  it  to  a  250-cc. 
Jena  beaker.  Add  10  cc.  of  nitric  acid,  5  cc.  of  hydrochloric 
acid,  and  5  cc.  of  water  and  heat  on  the  water-bath  until  the 
action  ceases.  Boil  on  the  hot  plate,  dilute  to  100  cc.  with  water, 
and  filter. 

*  Greenwood,  Eng.  and  Min.  Jour.,  96,  1175. 

fSmoot,  Eng.  and  Mining  Jour.,  96,  1175. 

t  Greenwood,  Eng.  and  Min.  Jour.,  76,  1175. 


THE  PLATINUM  METALS  251 

The  residue  may  contain  palladium  oxides;  it  should,  there- 
fore, be  boiled  with  3  cc.  of  formic  acid  (CH2O2)  and  5  cc.  of 
water  to  reduce  the  oxides  to  metallic  palladium,  which  is  then 
dissolved  by  the  treatment  above. 

Evaporate  the  filtrate  with  repeated  additions  of  nitric  acid 
to  expel  all  hydrochloric  acid,  dilute  the  solution  to  100  cc.  and 
add  25  cc.  of  a  10  per  cent  solution  of  mercuric  cyanide,  Hg(CN)2. 
Boil  a  few  minutes  and  let  it  stand  over  night. 

Pd(N03)2+Hg(CN)2=Pd(CN)2+Hg(N03)2. 

Filter  and  wash  with  a  1  per  cent  solution  of  mercuric  cyanide. 
Burn  in  a  porcelain  or  silica  crucible. 

Pd(CN)2+O2  =PdO2+2CN. 

Boil  the  residue  with  50  cc.  of  a  20  per  cent  solution  of  for- 
mic acid,  filter  in  a  weighed  Gooch  crucible  and  weigh  as  Pd. 

Pd02+2CH202  =Pd+2H2O+2C02. 

If  the  material  is  low  in  Pd,  begin  the  determination  with  several 
portions  of  0.5  gin.  each  and  combine  them  at  the  end  to  obtain  a  weigh- 
able  quantity  of  Pd. 


THE  .PLATINUM  METALS 
METHOD  OF  DEVILLE  AND  STAS  * 

Fuse  5  gms.  of  the  alloy  with  50  gms.  of  lead  in  a  cruci- 
ble of  purified  retort  carbon.  Hold  at  a  temperature  of  at 
least  1000°  C.  for  four  or  five  hours.  Boil  the  resulting  alloy 
with  very  dilute  nitric  acid,  filter  and  wash.  Retain  the  filtrate 
(see  below).  Boil  the  black  residue  with  very  dilute  aqua 
regia;  nitric  acid  (1)  :  hydrochloric  acid  (4)  :  water  (45).  Filter 
and  add  the  filtrate  to  the  nitric  acid  solution  above. 

*  Menschutkin,  "  Anal.  Chem.,"  164. 


252  METALLURGICAL  ANALYSIS 

Fuse  the  residue  of  lustrous  flakes  which  contains  all  the 
indium  and  ruthenium  with  3  gms.  of  potassium  nitrate  and  10 
gms.  potassium  carbonate.  Cool  and  extract  the  fusion  with 
water.  Transfer  the  solution  and  residue  to  a  tall  cylinder  and 
let  the  residue  settle.  Decant  the  clear  solution  and  wash  the 
residue  with  a  dilute  solution  of  sodium  carbonate  and  sodium 
hypochlorite  until  the  wash  is  no  longer  yellow.  Pour  these 
solutions  into  a  retort,  pass  chlorine  gas  into  the  solution  to 
saturate  it,  and  distill  into  a  flask  containing  water,  hydrohloric 
acid  and  alcohol  (purified  by  distillation  over  potassium  oxide). 

Perruthenic  acid  passes  over  into  the  flask  and  is  converted 
to  ruthenium  chloride.  Evaporate  the  distillate  to  dryness 
and  reduce  to  metallic  ruthenium  in  hydrogen.  The  residue 
in  the  retort  and  that  on  the  filter  contain  all  the  iridium.  Boil 
them  in  sodium  hydroxide  and  alcohol;  the  iridium  oxide  obtained 
is  purified,  reduced  in  hydrogen,  and  weighed  as  iridium. 

Analysis  of  Nitric  Acid  and  Aqua  Regia  Solutions.  Add 
to  these  solutions  combined  (which  contain  all  the  Pb,  Cu,  Pd, 
Rh,  Os)  just  enough  H^SCU  from  a  burette  to  precipitate  the 
lead.  Evaporate  the  solution  to  dryness.  Treat  the  residue 
with  hydrochloric  acid.  Filter  off  the  lead  sulphate.  To  the 
filtrate  add  ammonium  chloride,  filter,  dry  the  precipitate  at 
a  low  temperature  and  reduce  to  metals  with  hydrogen.  Fuse 
the  spongy  metals  with  acid  potassium  sulphate.  Platinum  is 
not  dissolved.  Dissolve  the  fusion  with  cold  water  and  filter 
off  the  platinum  and  weigh  it.  To  the  filtrate  add  mercuric 
cyanide  to  precipitate  Pd(Cn)2.  Filter,  and  complete  the  deter- 
mination for  palladium  according  to  the  method  on  p.  250. 

Add  formic  acid  to  the  filtrate  to  precipitate  Rh,  filter,  and 
weigh  as  Rh.* 

*  Mylius  and  Forster,  Berichte  der  deutschen  chem.  Gesellschaft,  25, 
665. 


COAL  253 


ANALYSIS   OF   FLUXES 

Limestone.     For  the  analysis  of  limestone  see  page  160. 

Silica.  Materials  high  in  silica  and  silicates  generally  may  be 
analyzed  by  following  the  method  for  clay,  page  286.  For  the 
determination  of  silica  in  such  materials  a  sample  of  0.5  gm. 
should  be  taken. 

Iron  Oxide.  Fluxes  high  in  ferric  oxide  are  analyzed  by  the 
methods  used  for  iron-ore,  page  50,  et  seq.  The  quantity  of 
Fe  multiplied  by  the  factor  1.4298  will  give  the  weight  of 

Fe2O3. 

For  methods  for  other  materials  see  the  Index. 

ANALYSIS   OF  FUELS 
COAL 

Sampling.*  The  sampling  of  coal,  if  the  determinations  of 
ash  are  to  agree  within  1  per  cent,  requires  greater  care  than  is 
usually  exercised  in  the  sampling  of  iron  ore;  that  is,  the  total 
original  sample  should  be  larger  and  it  should  be  made  up  of  a 
greater  number  of  individual  samples. 

Iron  ores  are  usually  not  sampled  with  so  much  care  as  is 
demanded  of  the  lowest  grade  material  referred  to  in  the  table 
on  page  11,  but  by  numerous  tests  it  has  been  shown  that  analyses 
of  coal  are  practically  worthless  if  the  coal  has  not  been  sampled 
at  least  as  carefully  as  is  required  for  "  low-grade  or  uniform  ore." 
Therefore,  the  figures  in  column  2,  page  11,  should  be  the  guide 
in  taking  the  original  sample  and  in  crushing  for  its  reduction. 
The  method  for  the  crushing,  dividing,  and  final  grinding  of  iron 
ore,  page  48,  should  be  used  for  the  preparation  of  the  sample 
of  coal.  For  the  fine  grinding  of  coal,  it  should  first  be  air-dried 
and  care  should  be  taken  that  the  grinder  does  not  become  heated 

*  Bailey,  Jour.  Ind.  and  Eng.  Chem.,  1,  176  (1909).  J.  A.  Holmes, 
U.  S.  Bureau  of  Mines,  Technical  Paper  1,  1911. 


254  METALLURGICAL  ANALYSIS 

since  oxidation  of  some  of  the  constituents  of  the  coal  begin 
at  a  comparatively  low  temperature.  A  ball  mill  of  porcelain 
is  recommended  for  the  fine  grinding  (see  Fig.  14  p.  14).  After 
the  coal  passes  a  12-mesh  screen,  it  is  put  in  the  jar  with  inch 
quartz  pebbles,  or  porcelain  balls,  and  the  jar  is  rotated  until 
the  coal  will  pass  a  60-mesh  sieve. 

PROXIMATE  ANALYSIS  OF  COAL 

In  the  valuation  of  coal  for  technical  purposes  it  is  much 
more  desirable  to  know  how  much  of  the  coal  is  ash,  fixed  car- 
bon, and  volatile  matter  than  to  know  the  percentage  of  the 
several  component  chemical  .elements.  By  the  proximate  anal- 
ysis, the  moisture,  volatile  matter,  fixed  carbon,  and  ash  are  de- 
termined. It  also  usually  includes  the  determination  of  sulphur.* 

Moisture.  Weigh  1  gm.  of  the  finely  powdered  coal  and 
transfer  it  to  a  porcelain  crucible  (18  mm.X40  mm.).  Place 
it  in  an  air-bath  and  heat  one  hour  at  105°  C.  in  a  current  of 
dry  air.  Remove  the  crucible  from  the  air-bath,  cover  it,  place 
it  in  a  desiccator  over  sulphuric  acid  and,  when  it  is  cool,  weigh 
it.  The  loss  in  weight  multiplied  by  100  gives  the  percentage 
of  moisture. 

Volatile  Matter. 

The  quantity  of  volatile  matter  that  a  coal  yields  depends  upon  the 
degree  of  heat  and  the  length  of  time  it  is  applied,  the  size  of  the  cru- 
cible in  which  it  is  heated,  etc.;  therefore,  in  order  that  results  may  have 
a  comparative  value,  it  is  necessary,  always,  to  carry  out  the  operation, 
as  nearly  as  possible,  under  the  same  conditions. 

A  committee  appointed  by  the  American  Chemical  Society  to  stand- 
ardize coal  analysis  recommended  the  following  method: 

Weigh  1  gm.  of  the  fresh,  powdered,  undried  sample  and 
place  it  in  a  20-gm.  or  30-gm.  platinum  crucible  which  has  a 
tightly  fitting  cover.  Heat  over  the  full  flame  of  the  Bunsen 

*  U.  S.  Bureau  of  Mines,  Technical  Paper  8. 


PEOXIMATE  ANALYSIS  OF  COAL  255 

burner  seven  minutes.  The  crucible  should  be  supported  on 
a  platinum  triangle  with  the  bottom  6  to  8  cm.  above  the  top 
of  the  burner.  The  flame  should  be  20  cms.  high,  when  burn- 
ing free,  and  should  be  protected  from  draughts.  The  carbon 
which  collects  on  the  outside  of  the  cover  should  be  burnt  off, 
but  not  that  which  is  deposited  on  the  inside.  Cool  and  weigh. 
From  the  loss  in  weight  subtract  the  moisture  previously  deter- 
mined to  obtain  volatile  combustible  matter. 

In  1913  the  Committee  recommended  the  following  methods: 
Volatile  Matter.  1.  Weigh  1  gm.  of  coal  and  place  it  in  a 
10-gm.  crucible  with  a  capsule  cover,  that  is,  one  that  fits  inside 
the  crucible,  and  not  on  top.  Place  the  crucible  on  a  platinum  or 
nichrome  wire  tripod  in  a  muffle  maintained  at  a  heat  of  approx- 
imately 950°  C.  and  leave  it  there  seven  minutes.  When  the 
flame  from  the  volatile  combustible  matter  disappears,  gently 
tap  the  cover  to  seal  the  crucible  and  exclude  the  air.  At 
the  expiration  of  seven  mimltes  withdraw  the  crucible,  cool  in 
a  desiccator,  and  weigh. 

2.  Weigh  1  gm.  of  coal  and  place  it  in  a  20-gm.  crucible  with 
capsule  cover.  Place  the  crucible  in  the  flame  of  a  No.  4  Meker 
burner,  which  gives  a  flame  15  cms.  high.  The  bottom  of  the 
crucible  should  be  1  cm.  above  the  top  of  the  burner  and  the  tem- 
perature inside  the  crucible  should  be  from  900°  to  950°  C. 
When  the  flame  from  the  volatile  combustible  matter  disappears, 
tap  the  cover  gently  to  exclude  the  air.  At  the  expiration  of 
seven  minutes,  place  the  crucible  in  a  desiccator  to  cool.  When 
cool,  weigh.  From  the  loss  in  weight  deduct  the  moisture  pre- 
viously determined. 

Coke.  If  the  residue  in  the  crucible  is  a  firm  coherent  mass, 
the  coal  is  a  coking  coal  and  the  wieght  of  the  mass  may  be  used 
to  calculate  the  percentage  of  coke  the  coal  will  produce. 

Ash.  If  coal  is  free  from  the  carbonates  of  calcium, 
magnesium,  etc.,  the  ash  may  be  determined  by  burning  off, 
with  the  crucible  uncovered,  all  the  carbonaceous  matter  from 


256  METALLURGICAL  ANALYSIS 

the  sample  in  which  moisture  was  determined,  or  from  a  fresh 
sample,  and  weighing  the  residue.  The  burning  should  begin 
over  a  very  low  flame.  The  carbon  is  more  easily  burned  from 
this  sample  than  from  the  compact  mass  of  coke. 

If  the  sample  contains  carbonates,  some  of  the  C(>2  will 
be  driven  off  when  the  carbon  is  burned;  the  residue  will,  there- 
fore, not  truly  represent  the  ash.  It  is  necessary  in  such  a  case 
to  determine  the  C02  in  a  separate  sample,  by  taking  a  5-gm. 
sample  of  the  coal  and  treating  it  according  to  the  method  on 
on  page  166  for  the  determination  of  C02  in  limestone.  From 
the  weight  of  CO2  calculate  its  equivalent  in  C.  The  factor  is 
0.2727. 

When  the  carbon  has  been  burned  from  a  1-gm.  sample, 
the  ash  is  moistened  with  a  few  drops  of  dilute  H2SO4  (1:1) 
and  carefully  heated  to  a  temperature  of  750°  C.  and  held  at 
that  temperature  five  minutes.  It  is  then  cooled  in  a  desiccator 
and  weighed.  Multiply  the  equivalent  of  the  C02  in  C  by  3 
and  subtract  this  from  the  weight  of  the  ash  to  convert  the 
weight  of  sulphate  to  its  equivalent  weight  of  carbonate,  since 
that  is  the  form  in  which  it  exists  in  the  coal. 

Fixed  Carbon.  The  weight  of  ash  subtracted  from  the  weight 
of  coke  will  give  the  fixed  carbon;  or  the  sum  of  the  moisture, 
volatile  matter,  and  ash  deducted  from  the  original  weight  of 
the  sample  (1  gm.)  will  give  the  fixed  carbon. 

SULPHUR  IN  COAL 

The  proximate  analysis  of  coal  usually  includes  the  determi- 
nation of  sulphur.  The  method  of  Eschka,  as  modified  by  the 
Committee  of  the  American  Chemical  Society  on  Coal  Analysis, 
is  an  excellent  one.* 

Reagents.     Eschka  mixture.     Two  parts  of  light  dry  mag- 

*  G.  L.  Heath,  Jour.  Amer.  Chem.  Soc.,  20,  630;  21,  1127.  A.  H.  White, 
"  Gas  and  Fuel  Analysis,"  205. 


SULPHUR  IN  COAL  257 

nesium  oxide  (MgO)  and  1  part  dry  sodium  carbonate  (Na2CO3) 
thoroughly  mixed  by  passing  them  at  the  same  time  through  a 
40-mesh  screen. 

Bromine  water.     Water  saturated  with  Br. 

Barium  chloride  solution.  A  10  per  cent  solution  of  BaCl2 
in  water. 

S  in  Coal.  Weigh  1.3737  gms.  and  mix  it  on  glazed  paper 
with  6  gms.  of  the  Eschka  mixture. 

As  the  sulphur  in  the  coal  burns,  it  is  absorbed  by  the  sodium  car- 
bonate. Magnesium  oxide  renders  the  mixture  porous,  so  that  air  is 
more  freely  admitted.  It  also  prevents  any  tendency  of  the  coal  to 
cake. 

Transfer  the  mixture  to  a  25  cc.  porcelain  crucible  and  add, 
as  a  cover,  about  2  gms.  of  the  Eschka  mixture.  Heat  the 
crucible  gently  with  an  alcohol  lamp,  stirring  occasionally  with 
a  platinum  wire,  for  about  thirty  minutes,  or  until  the  black 
particles  of  carbon  have  disappeared. 

The  sulphur,  being  oxidized,  replaces  C02  in  the  Na2C03  and  forms 
the  sulphate,  and  probably  some  sulphite,  of  sodium. 

Instead  of  using  an  alcohol  lamp,  the  burning  out  of  the  carbon  may 
be  accomplished  in  a  gas  muffle,  if  it  is  heated  gradually,  and  if  a  blank 
is  run  in  the  muffle,  at  the  same  time,  to  determine  the  quantity  of  sul- 
phur absorbed  from  the  gas.  It  is  desirable,  in  any  case,  to  run  a  blank 
to  determine  the  amount  of  sulphur  in  the  reagents. 

Cool  the  crucible  and  transfer  the  contents  to  a  beaker, 
using  hot  water.  Add  about  200  cc.  of  hot  water,  and  digest 
for  thirty  to  forty  minutes  at  the  boiling-point  or  near  it,  stirring 
occasionally.  Filter  and  wash  the  residue  several  times  by 
decantation  with  hot  water,  and  finally,  transfer  and  wash  the 
residue  on  the  filter. 

Parr  *  has  found  that  all  the  sulphur  is  not  extracted  by  treatment 
with  water  alone.  After  extraction  with  water  he  treats  the  residue 
with  acid  to  recover  the  remaining  sulphur. 

*  J.  Ind.  and  Eng.  Chem.,  1,  690. 


258  METALLURGICAL  ANALYSIS 

To  the  filtrate  add  20  cc.  of  bromine  water  and  enough  con- 
centrated hydrochloric  acid  to  make  the  solution  slightly  acid. 

Bromine  oxidizes  sodium  sulphite  to  sulphate. 
See  sulphur  in  ore,  page  73. 

Heat  the  solution  to  boiling  and  add,  drop  by  drop,  while 
stirring,  10  cc.  of  hot  barium  chloride  solution.  Boil  the  solu- 
tion gently  fifteen  minutes  and  let  it  stand,  a  little  below  the 
boiling-point,  two  hours  or  longer.  Filter  and  wash,  first  with 
hot  water  acidulated  with  hydrochloric  acid  (1  :  1000),  and  then 
with  hot  water,  until  the  washings  are  free  from  hydrochloric 
acid.  Burn  the  filter  in  a  platinum  crucible,  cool  in  a  desiccator, 
and  weigh.  Make  the  correction  indicated  by  the  blank  and 
multiply  the  result  by  10. 

RAPID  METHOD  FOR  SULPHUR  IN  COAL  BY  THE 
TURBIDIMETER  * 

After  the  determination  of  the  calorific  power  o.  the  coal 
with  the  bomb  calorimeter  (see  p.  262),  wash  out  the  bomb 
carefully  with  hot  water.  Titrate  for  acidity.  Add  5  cc.  of  hydro- 
chloric acid  (1:2)  and  heat  to  boiling.  Cool  and  precipitate  the 
sulphur  in  the  cold  with  a  solution  of  barium  chloride  to  which 
has  been  added  a  little  oxalic  acid. 

The  precipitate  is  very  finely  divided  and  does  not  settle  readily. 

Dilute  to  the  mark  in  a  graduated  flask,  mix,  and  take  out 
an  aliquot  part  of  the  turbid  solution  and  compare  it  with  a 
standard  which  has  been  prepared  in  the  same  way  from  a 
sample  in  which  the  sulphur  is  known.  (See  Colorimetry  p.  42.) 
This  method  gives  somewhat  lower  results  than  the  Eschka 
method.  The  sulphur  in  the  standard,  therefore,  should  have 
been  determined  by  the  Eschka  method  and  the  standard 
burnt  in  the  calorimeter  in  the  usual  way. 

*Parr,  Jour.  Amer.  Chem.  Sec.,  26,  1139  (1904);  Jour.  Ind.  and  Chem. 
Eng.,  1,  689  (1909). 


HYDROGEN  AND  OXYGEN   IN  COAL  AND  COKE        259 

ULTIMATE   ANALYSIS   OF   COAL 
HYDROGEN  AND  OXYGEN  IN  COAL  AND  COKE 

Weigh  about  0.25  gm.  of  the  coal,  place  it  in  a  combustion 
boat,  and  burn  in  a  combustion  furnace  in  a  current  of  pure 
dry  oxygen.  Pass  the  products  of  combustion  through,  first, 
an  absorption  bulb  containing  H2SO4,  which  removes  the  water, 
and  then  through  a  similar  bulb  containing  KOH  solution,  which 
absorbs  the  CO2.  The  bulbs  are  weighed  before  and  after 
combustion.  '  From  the  weights  of  H^O  and  C02  found  the  H 
and  C  are  calculated. 

NITROGEN  IN  COAL 

The  percentage  of  nitrogen  in  coal  indicates  the  quantity 
of  ammonia  that  may  be  recovered  as  a  by-product  in  coke- 
making.  Nitrogen  is  determined  by  the  Kjeldahl  method.* 

N  in  Coal.  Place  1  gm.  of  coal  in  a  500-cc.  Kjeldahl  flask 
with  30  cc.  of  dilute  sulphuric  acid  (1  :  84)  and  0.6  gm.  of  mer- 
cury and  boil  until  the  solution  is  nearly  colorless  (three  hours). 
Add  potassium  permanganate  crystals  gradually  until  the  solu- 
tion becomes  permanently  green. 

Cool,  dilute  the  solution  to  about  200  cc.  with  cold  water. 
Add  25  cc.  of  potassium  sulphide  solution  (40  gms.  KsiS  per 
liter)  to  precipitate  the  mercury.  Add  1  gm.  of  granulated 
zinc  to  prevent  bumping  and  about  0.5  gm.  of  paraffine  to  pre- 
vent frothing.  Add  saturated  solution  of  sodium  hydroxide  to 
distinct  alkalinity  (80  ec.  to  100  cc.). 

Connect  the  flask  at  once  with  the  condenser  and  distil 
the  ammonia  into  a  measured  quantity  of  standard  sulphuric 
acid  solution  (1  cc.  equivalent  to  0.05  gm.  N)  to  which  has 
been  added  cochineal  indicator.  Continue  the  distillation  until 

*  Technical  Paper  8,  U.  S.  Bureau  of  Mines. 


260  METALLURGICAL  ANALYSIS 

200  cc.  have  passed  over,  then  titrate  the  excess  acid  with  stand- 
ard ammonia  solution.  The  two  solutions  should  be  made  so 
that  20  cc.  NH4OH  solution  =  10  cc.  H2SO4  solution. 

OXYGEN  IN  COAL 

Oxygen  is  determined  by  difference.  The  sum  of  the  per- 
centages of  carbon,  hydrogen,  nitrogen,  sulphur,  and  ash  are 
deducted  from  100;  the  remainder  is  assumed  to  be  oxygen. 

PHOSPHORUS  IN  COAL 

Weigh  6.52  gms.  of  the  coal  and  transfer  it  to  a  platinum 
crucible.  Place  the  crucible  in  a  muffle  and  burn  the  carbon. 
Add  to  the  ash  about  six  times  its  weight  of  sodium  carbonate 
and  0.2  gm.  of  sodium  nitrate.  Fuse  with  a  blast  lamp.  Cool 
and  dissolve  the  fusion  in  water  and  hydrochloric  acid.  Evap- 
orate the  solution  to  dryness.  Dissolve  the  residue  in  dilute 
hydrochloric  acid,  filter,  and  determine  the  phosphorus  in  the 
filtrate  according  to  one  of  the  methods  for  phosphorus  in  ore 
(p.  75.) 

CALORIFIC  POWER  OF  COAL 

The  calorie  is  the  quantity  of  heat  required  to  raise  1  gm.  of 
water  1°  C.  (between  0°  and  100°).  The  calorific  value,  or 
power,  of  a  coal  is  expressed  by  the  number  of  calories  that  1 
gm.  of  the  coal  will  yield  when  burnt  in  a  calorimeter.  A 
calorimeter  of  the  usual  type  consists  of  a  bomb  of  steel  or 
alloy  in  which  the  coal  is  burnt,  and  its  enclosing  vessel  of  about 
4  liters  capacity  which  holds  a  definite  weight  of  water,  in 
which  the  bomb  is  submerged  while  a  determination  is  being 
made.  This  vessel  is  usually  made  of  copper,  plated  with 
nickel  to  diminish  the  loss  of  heat  by  radiation,  and  is  pro- 
vided with  a  stirrer  and  an  accurate  thermometer  graduated  to 


CALORIFIC  POWER  OF  COAL 


261 


hundrcdths  of  a  degree  centigrade.  The  bomb  in  some  cal- 
orimeters is  held  in  place  centrally  in  the  inner  of  two  con- 
centric fiber  pails  to  render  the  passage  of  heat  between  the 
water  in  the  calorimeter  and  the  atmosphere  of  the  room  slow  and 
uniform. 

The  bomb  is  usually  made  of  steel  and  is  lined  with  enamel 
or  nickel,  or,  for  very  accurate  work,   with  gold  or  platinum. 
Parr  *  has  made  a  bomb  of  an  alloy  of  nickel,  copper,  tungsten, 
etc.,  which   resists  well    the   action  of    nitric 
and  sulphuric  acids  and,  therefore,  needs  no 
lining.     It  is  provided   with  rubber  gaskets, 
well  protected  from  the  heat,  and  is  there- 


FIG.  93.— Bomb  for 
Calorimeter. 


FIG.  94. — Calorimeter  Bomb  with 
Fittings. 


fore  more  satisfactory  to  operate  and  to  keep  in  working  con- 
dition than  are  other  types  of  bombs,  which  have  metal  valves 
and  gaskets.  (Figs.  93  and  94.) 

The  bomb  is  provided  with  a  tightly  fitting  cover,  held  firmly 
in  place  on  the  gasket  by  a  collar  screwed  down  on  the  outside. 
Through  a  valve  in  the  cover,  oxygen  is  admitted  for  combus- 
tion. The  capsule  in  which  the  coal  is  placed  for  combustion  is 
supported,  near  the  center  of  the  bomb,  on  one  of  the  electrodes, 
which,  in  turn,  is  attached  to  the  cover.  The  other  electrode 
pierces  the  cover  and  is  insulated  from  it. 

*  Jour.  Ind.  and  Eng.  Chem.,  4,  746  (1912). 


262  METALLURGICAL  ANALYSIS 

In  the  calorimeter  vessel,  a  weighed  quantity  of  water  is 
placed  (usually  about  2000  cc.),  in  which  the  bomb  is  submerged 
for  the  combustion.  Midway  between  the  bomb  and  the  side 
of  the  vessel,  an  accurate  thermometer,  which,  with  the  aid  of  a 
cathetometer  and  telescope  may  be  read  to  thousandths  of  a 
degree,  is  introduced  through  the  cover  of  the  calorimeter  and 
fixed  in  place  with  the  bulb  of  the  thermometer  opposite  the 
center  of  the  bomb.  While  a  determination  is  being  made,  the 
water  is  thoroughly  stirred  at  a  uniform  rate  with  a  stirrer  which 
projects  through  a  hole  in  the  cover.  The  air  space  between  the 
inner  and  outer  pails  serves  as  an  insulation  from  the  heat  of  the 
room.  For  accurate  work,  this  space  is  also  filled  with  water, 
and,  in  that  case,  it  also  is  provided  with  stirrer  and  thermometer. 

Calorific  Power  of  Coal.  Weigh  in  a  shallow  platinum 
capsule  about  1  gm.  of  coal,  and  place  it  in  position  on  the  elec- 
trode. Weigh  a  length  of  about  5  cms.  of  36  B.  &  S.  gauge  iron 
wire  and  with  it  connect  the  two  electrodes  above  the  capsule, 
bending  a  loop  of  wire  down  to  touch  the  coal,  but  not  the 
capsule. 

Powdered  bituminous  coal  burns  so  violently  that  some  of  the  dust 
may  be  thrown  from  the  capsule  before  it  is  burnt.  The  powder  should, 
therefore,  be  compressed  into  a  pellet  before  weighing. 

Place  in  the  bomb  a  few  drops  of  water  to  absorb  the 
nitric  acid  which  is  produced  by  the  combustion.  Put  the 
cover  in  place  on  the  bomb,  taking  care  not  to  disturb  the 
position  of  the  capsule.  With  the  spanner,  screw  the  ring  down 
to  hold  the  cover  firmly  hi  place,  attach  the  oxygen  tank  with  a 
flexible  metal  tube  provided  with  a  pressure  gauge,  open  the 
valve  of  the  bomb  and  then  the  valve  of  the  oxygen  cylin- 
der, and  let  the  oxygen  flow  in  gently  until  the  gauge  indicates 
20  to  25  atmospheres.  Close  the  valve  of  the  oxygen  tank 
and  then  the  valve  of  the  bomb  and  disconnect  the  cylinder. 
Weigh  in  the  calorimeter  2000  gms.  of  water,  which  should  be 
about  2°  or  3°  C.  above  the  room  temperature.  The  quan- 


CALORIFIC  POWER  OF  COAL  263 

tity  of  water  used  may  be  such  that  when  combined  with  the 
water  value  of  the  calorimeter  the  total  will  be  equivalent  to 
3000  gms.  of  water. 

If  only  an  approximate  determination  is  to  be  made,  and  no  correc- 
tion for  loss  of  heat,  the  water  in  the  calorimeter  should  be  about 
3°  C.  below  the  room  temperature,  but  not  low  enough  to  precipitate 
moisture  from  the  atmosphere  on  the  outside  of  the  calorimeter. 

The  gain  and  loss  of  heat  due  to  the  deposition  and  later  evaporation 
of  this  moisture  would  interfere  with  the  gradual  and  uniform  change 
of  temperature  which  is  desirable  within  the  calorimeter. 

Place  the  bomb  in  the  center  of  the  calorimeter,  attach- 
ing the  electric  wires  for  ignition.  Put  on  the  cover,  and  adjust 
the  thermometer  and  the  stirrer. 

.  The  thermometer  must  be  made  especially  for  this  purpose  and  must 
be  carefully  calibrated.  After  recording  the  readings  of  the  thermometer, 
the  corrected  readings  from  the  certificate  must  be  added. 

Stir  two  minutes  and  then  read  the  thermometer  and  record 
the  reading.  Continue  the  stirring  at  a  uniform  rate  and  read  the 
thermometer  each  minute  for  five  minutes.  The  thermometer 
should  gradually  fall,  as  the  heat  of  the  water  passes  out  to  the 
air  of  the  room.  On  the  minute  that  the  fifth  reading  of  the 
thermometer  is  taken,  close  the  electric  circuit  to  ignite  the  coal. 
The  current  from  dry  cells  at  about  12  volts  ignites  the  coal 
promptly  by  heating  the  small  iron  wire.  Continue  stirring 
and  read  the  thermometer  every  minute,  for  at  least  ten  minutes 
after  ignition.  Note  carefully  the  maximum  temperature  and 
the  time  of  its  occurrence. 

After  all  the  readings  have  been  taken  and  recorded,  remove 
the  bomb  from  the  calorimeter,  open  the  valve  to  relieve  the 
pressure,  and  take  off  the  cover.  Rinse  out  the  bomb  carefully 
with  hot  water  and  titrate  the  acid  in  the  solution  with  a  standard 
alkali  solution. 

If  the  sulphur  in  the  coal  has  not  been  determined,  after 
titrating  the  acid,  which  is  a  combination  of  nitric  and  sul- 


264  METALLURGICAL  ANALYSIS 

phuric  acids,  make  the  solution  acid  with  hydrochloric  acid  and 
determine  the  sulphur  by  precipitating  it  with  barium  chloride. 
(See  p.  73.) 

Weigh  the  lengths  of  unburnt  wire  to  determine  how  much 
has  been  burnt. 

To  prevent  rusting  of  the  valve,  the  bomb  should  not  stand  wet 
too  long,  but  should  be  carefully  dried  in  an  air-bath. 

Corrections.  The  maximum  reading  of  the  thermometer 
cannot  be  taken  as  the  correct  figure  by  which  to  multiply  the 
weight  of  water  in  the  calorimeter  and  its  water  value,  for  there 
has  been  (1)  a  loss  of  heat  from  the  calorimeter  while  the 
thermometer  has  been  rising;  on  the  other  hand  deductions 
must  be  made  (2)  for  the  sulphur,  which  in  ordinary  combustion 
is  oxidized  chiefly  to  862,  but  in  the  bomb  is  oxidized  almost 
entirely  to  SOs;  (3)  for  oxidation  of  some  nitrogen  to  nitric 
acid,  which  would  not  take  place  in  the  ordinary  burning  of  the 
fuel  on  a  grate;  and  (4)  for  the  burning  of  the  iron  ignition 
wire. 

1.  The  correction  for  the  loss  of  heat  by  radiation  may  be 
done  graphically  by  the  method  of  Holman  *  described  by  Howe.f 
Plot  on  cross-section  paper,  on  a  large  scale,  the  corrected  read- 
ings of  the  thermometer  as  ordinates,  and  the  times  of  the  read- 
ings as  abscissas,  and  draw  a  line  through  these  points,  as  shown 
in  Fig.  95.  The  line  i-m-o-p-r  shows  the  maximum  reading  at 
o.  Through  o  draw  a  line  parallel  to  pr  and  project  it  to  cut 
the  ordinate  through  m  at  n.  The  number  of  degrees  represented 
by  the  line  mn  is  the  corrected  rise  in  temperature  due  to  the 
combustion.  Multiply  the  weight  of  water  in  the  calorimeter 
added  to  the  water  value  of  the  calorimeter  by  the  rise  in  tem- 
perature represented  by  the  line  mn',  the  result  will  be  the 
total  number  of  calories  produced  by  the  combustion.  From 

*  "  Physical  Laboratory  Notes,"  46  (1887). 

t  "  Metallurgical  Laboratory  Notes,"  35  (1902). 


CALORIFIC  POWER  OF  COAL 


265 


this  total  must  be  deducted  the  heat  of  formation  of  the  acids 
and  of  the  magnetic  oxide  produced  by  the  burning  of  the  iron 
wire. 

2.  The  correction  for  the  higher  oxidation  of  sulphur  in  the 
bomb  cannot  be  made  with  absolute  accuracy,  for  the  quantity 
of  heat  produced  depends  not  only  upon  the  quantity  of  sul- 
phur present,  but  upon  the  form  in  which  it  occurs  and  the  com- 
pleteness of  oxidation.  It  is  customary,  however,  to  assume 


FIG.  95. — Graph  for  Correcting  Total  Rise  in  Temperature. 

that  all  the  sulphur  in  the  coal  is  in  the  form  of  pyrite,  and  to 
deduct  for  each  milligram  of  sulphur  2  calories.* 

3.  When  the  sulphur  present  has  been  calculated  to  sul- 
phuric acid,  deduct  it  from  the  total  acidity;  the  remainder 
is  nitric  acid  formed  by  the  oxidation  of  nitrogen.  The  forma- 
tion of  1  gm.  of  HNOs  produces  238  calories.  The  correction 
is  usually  not  more  than  8  calories,  f 

*  A.  H.  White,  "  Gas  and  Fuel  Analysis,"  231  (1913). 
t  Ibid.,  230. 


266  METALLURGICAL  ANALYSIS 

4.  When  1  gm.  of  iron  is  burnt  to  FeaO-i,  it  yields  1600 
calories;  therefore,  1.6  calories  must  be  deducted  for  every 
milligram  of  fuse  wire  burnt. 

Water  Value  of  the  Calorimeter.  Burn  in  the  calorimeter 
exactly  in  the  manner  described  for  coal,  either  2  gms.  of  pure 
cane-sugar,  C^lfeOn  (3945  calories  per  gm.),  1.5  gms.  benzoic 
acid,  C7H602  (6321  calories  per  gm.),  or  1  gm.  camphor,  CgHieCO 
(9290  calories  per  gm.)  and  make  the  corrections  which  are  made 
in  the  method  for  coal,  except  that  for  sulphuric  acid,  which  is 
omitted.  Deduct  the  number  of  calories  thus  determined  from 
the  calculated  value,  using  the  values  given  above.  The  dif- 
ference represents  the  heat  absorbed  by  the  calorimeter.  Divide 
this  number  by  the  total  corrected  rise  in  temperature  (mn. 
Fig.  95,  p.  22)  and  the  quotient  represents  the  equivalent  in 
water  of  the  calorimeter,  or  its  water  value. 

Formula  for  Calorific  Power.  The  method  for  calculating  the 
calorific  power  may  be  indicated  by  the  formula 


^_ 


C  =  the  calorific  power  of  the  material.     (Calories  produced  by 

burning  1  gm.); 

r  =  the  corrected  rise  in  temperature; 
W  =  the  weight  of  water  in  the  calorimeter  in  grams; 
w  =  the  water  value  of  the  calorimeter; 
JV  =  mgm.  of  nitric  acid; 
a  =  mgm.  of  sulphuric  acid; 
F  =  mgm.  of  iron  wire  burnt; 
S  =  weight  of  the  sample  of  coal  burnt. 

If  approximate  determinations  are  to  be  made,  and  no  corrections 
applied  for  loss  or  gain  from  the  heat  of  the  room,  the  error  will  be 
reduced  by  beginning  the  operation  with  the  water  in  the  calorimeter 
about  3°  C.  below  the  temperature  of  the  room,  for,  since  the  rise  of  tem- 
perature due  to  combustion,  under  this  condition,  will  bring  the  cal- 


CALORIFIC  POWER  OF  COAL  267 

orimeter  to  about  room  temperature,  there  will  be  only  a  slight  tendency 
for  gain  or  loss  to  the  calorimeter. 

Dickinson's  Formula.  For  calculating  the  calorific  power 
by  Dickinson's  formula,  the  water  in  the  calorimeter  should 
be  about  3°  C.  below  room  temperature  when  the  operation 
begins. 

The  thermometer  is  read  every  minute  for  five  minutes, 
or  until  the  rise  in  temperature  is  uniform;  then,  on  the  fifth 
minute,  close  the  circuit  to  ignite  the  coal  and  note  the  time 
a  and  the  temperature  t.  To  the  temperature  t  (corrected) 
add  60  per  cent  of  the  expected  total  rise  in  temperature  and  call 
iU2. 

The  total  rise  of  the  thermometer  for  any  calorimeter  is  nearly  con- 
stant if  the  tests  are  always  made  on  the  same  quantity  of  coal — 60 
per  cent  of  the  expected  rise  is  therefore  based  upon  previous  determina- 
tions. 

When  the  thermometer  has  risen  to  fe,  note  the  time  b. 

Continue  reading  the  thermometer  every  minute  for  about 
ten  minutes  until  the  change  of  temperature  has  become  uniform. 
Observe  which  of  these  readings  is  the  first  one  in  the  period 
of  uniform  change  and  mark  it  c. 

Now  find  the  rate  of  rise  in  temperature  r\  for  the  pre- 
liminary period,  that  is,  from  the  first  reading  up  to  a,  and  the 
rate  of  cooling  per  minute,  r2,  during  the  final  period,  that  is, 
from  c  to  the  end. 

Open  the  bomb,  wash  it  out,  and  determine  the  amount  of 
acid  formed  and  the  weight  of  wire  burnt  as  directed  on  page  263. 

From  the  above  data  calculate  the  calorific  power  according 
to  the  formula  given  below. 

ri  =  rate  of  rise  in  temperature  (preliminary); 
a  =  time  of  last  reading  preliminary  period; 
t  =  temperature  at  time  a; 
t2  =  t-\-QO  per  cent  of  expected  rise; 


268  METALLURGICAL  ANALYSIS 

6  =  time  when  thermometer  reads  fo; 

c  =  time  when  change  in  temperature  has  become  uniform 

after  combustion; 
tz  =  temperature  at  time  c; 
r2  =  rate  of  cooling  in  final  period; 

—  [fi(b  —  a)+Z]  =  total  temperature  rise  T. 


The  intervals  of  time  c  —  b  and  b—a  are  to  be  expressed  in 
minutes  and  tenths  of  minutes. 

T  multiplied  by  the  weight  of  water  in  the  calorimeter  plus 
its  water  value  equals  the  total  amount  of  heat  liberated. 
This  quantity  corrected  for  the  acid  and  FesCU  formed,  and 
divided  by  the  weight  of  coal  taken,  will  give  the  calorific  power. 

CALORIFIC  POWER  OF  COAL  BY  THE  PARR 
CALORIMETER  * 

In  the  Parr  calorimeter  the  coal  is  burnt,  not  by  oxygen 
under  compression,  but  by  oxygen  furnished  by  sodium  peroxide 
and  potassium  chlorate,  which  are  mixed  with  the  coal. 

The  following  reactions  are  believed  to  take  place: 

2Na2O2+   C  =  Na2CO3+Na20. 
Na2O2+H2  =  2NaOH. 

Since  there  is  no  gas  under  compression,  either  before  or 
after  the  combustion,  a  strong  bomb  is  not  required,  but  only 
a  comparatively  light  "  cartridge.  "  The  cartridge  is  placed 
in  a  cylindrical  brass  calorimeter  vessel,  which  is  insulated  from 
the  heat  of  the  room  by  two  concentric  fiber  pails.  The  tem- 
perature of  the  water  in  the  calorimeter  is  taken  with  an  accurate 
thermometer,  graduated  to  hundredths  of  a  degree,  and  the 
water  is  stirred  by  rotating  the  cartridge,  to  which  are  clamped 

*  Jour.  Amer.  Chem.  Soc.,  22,  646;   Jour.  Ind.  and  Eng.  Chem.,  1,  673. 


CALORIFIC  POWER  OF  COAL  BY  PARR  CALORIMETER    269 

propeller-like  wings.     A   belt  from  a  motor  drives   the   pulley 
attached   to  the  stem   of  the  cartridge,   the  cartridge  turning 
on  a  pivot  fixed  in  the  bottom  of 
the  calorimeter  vessel.     (Fig.  96.) 

Operation  of  the  Calorimeter. 
Weigh  0.5  gm.  of  the  coal  which 
has  been  ground  to  pass  a  100-mesh 
screen,  and  transfer  it  to  the  cart- 
ridge, in  which  has  already  been 
placed  1  gm.  of  finely  ground 
KC103.  Add  about  10  gm.  of 
Na2O2  (measured  in  a  scoop  fur-  FIG.  96.— Parr  Calorimeter, 
nished  with  the  calorimeter) .  Close 

the  cartridge  with  the  false  cover  and  shake  to  mix  the  coal 
and  reagents  thoroughly. 

The  Na202  must  be  fresh.  It  deteriorates  rapidly  on  exposure  to 
air  and  moisture. 

The  cartridge  must  be  thoroughly  dry  before  putting  in  the  charge. 

Attach  a  loop  of  34  or  36  B.  &  S.  gauge  iron  wire  to  the  termi- 
nals so  that  it  will  be  pressed  down  into  the  charge  when  the  cap 
is  put  on.  Screw  the  cap  on,  making  sure  there  are  no  leaks, 
for  a  little  water  in  the  bomb  would  spoil  the  determination  and 
might  cause  an  explosion.  Put  in  the  calorimeter  2000  gms. 
of  water  at  about  2°  C.  below  room  temperature. 

Place  the  cartridge  on  its  pivot,  adjust  the  cover,  thermometer, 
electric  wires  for  firing,  and  the  belt  on  the  pulley.  Start  the 
cartridge  rotating  at  about  100  revolutions  per  minute  and 
read  the  thermometer  every  minute  (see  p.  263).  After  four 
or  five  minutes,  when  the  rise  in  temperature  has  become 
uniform,  close  the  circuit  to  ignite  the  charge,  and  continue 
reading  the  thermometer  for  about  eight  minutes  after  igni- 
tion, noting  the  maximum  temperature  reached.  The  rise  in 
temperature  may  be  corrected  according  to  the  method  given 


270  METALLURGICAL  ANALYSIS 

on  page  265.  According  to  Professor  Parr  *  the  increase  in  tem- 
perature should  be  further  corrected  by  "  a  factor  made  up  of 
the  following  components  ": 


Each  per  cent  of  ash  is  multiplied  by 0.00275°  C. 

Each  per  cent  of  sulphur  is  multiplied  by 0.005°  C. 

Correction  for  heat  reaction  of  1  gm.  KClOs--  ,  0.130°  C. 
Heat  of  combustion  of  fuse  wire 0.008°  C. 

The  corrected  rise  in  temperature  T  is  multiplied  by  the  water 
in  the  calorimeter  (2000  gms.)  added  to  its  water  value,  which 
is  for  the  Parr  calorimeter  135.  Professor  Parr  found,  by  care- 
ful tests,  that  the  heat  evolved  in  burning  coal  in  oxygen  is 
73  per  cent  of  that  produced  when  the  coal  is  burnt  in  Na2C>2; 
therefore,  -the  calorific  power  C  may  be  calculated  from  the  fol- 
lowing equation: 

„_  7(2135)0.73 
W 

in  which  T  represents  the  corrected  rise  in  temperature  and  W 
the  weight  of  the  sample.  When  W  equals  0.5  gm.  the  calorific 
power  equals  73 117. 

CALORIFIC  POWER  FROM  THE  ULTIMATE  ANALYSIS 

The  calorific  power  of  coal  may  be  calculated  from  its  ultimate 
analysis  by  multiplying  the  percentage  of  each  of  its  constituent 
combustible  elements  by  its  calorific  power  and  taking  the  sum 
of  the  products.  The  following  correction,  however,  must  be 
made  for  hydrogen.  It  is  assumed  (Dulong's  formula)  that  all 
the  oxygen  in  coal  exists  in  combination  with  hydrogen  as  water; 
therefore,  a  sufficient  quantity  of  hydrogen  to  combine  with  all 

*  Jour  Ind.  and  Eng.  Chem.,  1,  673. 


PETROLEUM  271 

the  oxygen  present  as  H2O,  is  deducted  from  the  total  hydrogen 
before  multiplying  by  its  calorific  power.  Since  the  weight 
of  the  hydrogen  in  water  is  equal  to  one-eighth  of  the  weight 
of  the  oxygen,  deduct  from  the  percentage  of  hydrogen  one- 
eighth  of  the  percentage  of  the  oxygen  in  the  coal;  and  then 
calculate  the  calorific  power  as  follows: 

Percentage  CX8100(C  to  CC^)  — •  calories  produced  by  carbon. 

H-(J  percentage  of  O)X  34,500  (H  to  H2O,  liquid) 

=  calories  produced  by  hydrogen. 
SX2164(S  to  802)  =  calories  produced  by  sulphur. 
Take  the  sum  of  these  products  for  the  total  calories  produced  by 
1  gm.  of  the  coal. 

This  method  usually  gives  lower  results  than  those  obtained 
with  the  calorimeter.  The  difference  is  not  uniform,  but  the 
average  for  more  than  50  determinations  made  by  the  U.  S. 
Geological  Survey  is  about  1  per  cent. 

To  convert  calories  to  British  thermal  units  multiply  by  1.8. 

PETROLEUM 

Sampling.  If  the  oil  can  be  sampled  while  it  is  flowing  from 
a  pipe,  the  samples  should  be  taken  at  regular  intervals  with  a 
small  dipper  and  collected  in  a  pail.  If  the  oil  is  in  tanks  or  barrels, 
lower  a  long  tube,  which  is  open  at  both  ends,  vertically  into  the 
oil  until  it  touches  the  bottom  of  the  container,  close  the  lower 
end  of  the  tube  by  pressing  into  it  a  stopper  held  on  the  end  of 
wire  which  passes  through  the  tube;  or,  if  the  tube  is  small, 
close  tightly  the  upper  end  and  withdraw  it  with  the  sample. 
Instead  of  a  tube,  a  bottle  attached  to  a  rod  or  stick  may  be 
depressed  well  into  the  oil,  the  stopper  withdrawn  by  a  string, 
and  the  bottle  allowed  to  fill. 


272  METALLURGICAL  ANALYSIS 

FRACTIONAL  DISTILLATION  OF  CRUDE  PETROLEUM 

In  the  examination  of  crude  petroleum  the  oil  is  divided 
into  various  products  by  fractional  distillation  and  the  quantity, 
specific  gravity,  color,  etc.,  of  the  several  products  determined. 

The  crude  oil  is  placed  in  a  still  provided  with  a  thermometer 
which  has  its  bulb  opposite  the  outlet  of  the  still.  The  temper- 
ature is  raised  gradually  and  the  distillate  of  light  oil,  naphtha, 
gasolene,  etc.,  is  collected,  until  the  temperature  reaches  150°  C. 
This  distillate  is  removed  and  another  receiver  is  attached  to 
collect  the  illuminating  oil,  which  distils  over  while  the  heat  is 
gradually  increased  from  150°  to  300°  C.  After  the  illuminating 
oil,  the  lubricating  oil  is  collected  until  there  is  only  coke  left 
in  the  still. 

For  the  test,  Gray  *  recommends  the  following  method: 
Measure  from  2  to  4  liters  of  the  crude  petroleum  and  distil 
it  at  the  rate  of  5  to  10  cc.  per  minute  and  collect  the  distillate 
in  1  per  cent  fractions.  Take  the  fractions  of  more  than  58°  B. 
for  the  naphtha  fraction,  all  those  between  58°  and  36°  B.  for 
burning  oils,  and  those  below  36°  B.  for  lubricating  distillate; 
the  residue  is  coke. 

Sulphur  in  Petroleum.  Sulphur  is  best  determined  in 
petroleum  by  burning  the  oil  in  a  calorimeter  with  oxygen  under 
a  pressure  of  25  to  30  atmospheres,  washing  out  the  bomb, 
acidifying  the  washings  with  HC1,  and  precipitating  the  S  as 
BaSO4  with  BaCl2  solution. 

Calorific  Power  of  Liquid  Fuels.  Place  a  weighed  quantity 
of  the  liquid  in  a  narrow  platinum  crucible,  f 

If  the  liquid  is  burnt  in  a  shallow  capsule,  combustion  is  not  always 
complete. 

Above  the  liquid,  on  a  glass  platform  in  the  crucible,  place 
a  weighed  quantity  of  powdered  sugar  (3945  calories  per  gm.). 

*  "  Industrial  Chemistry,"  p.  522. 

t  Richards  and  Jesse:  Jour.  Amcr.  Chem.  Soc.,  32,  268. 


WATER  IN  OIL  273 

Place  the  crucible  in  the  bomb  of  a  calorimeter  with  the  fuse 
wire  adjusted  in  the  sugar  and  carry  out  the  operation  in  the 
manner  described  for  determining  the  calorific  power  of  coal  on 
page  262.  Of  course  the  number  of  calories  produced  by  the 
burning  of  the  sugar  must  be  deducted  from  the  total. 

WATER  IN  OIL 

Distil  200  gins,  of  the  oil  in  a  small  still  and  collect  the  dis- 
tillate until  the  temperature  reaches  150°  C.  Collect  the  water 
from  the  distillate  with  a  micropipette  and  weigh  it.  If  any 
drops  of  water  adhere  to  the  inside  of  the  condenser  and  do  not 
run  into  the  receiver,  wet  a  small  pellet  of  absorbent  cotton,* 
squeeze  it  as  dry  as  possible,  weigh  it,  fasten  it  to  a  wire,  and 
run  it  into  the  condenser  to  collect  the  drops,  weigh  it  again  and 
add  the  increase  in  weight  to  that  of  the  water  found  in  the  receiver. 

GAS  ANALYSIS 

Sampling.  A  tube  of  porcelain,-  fused  quartz,  or  glass  is 
inserted  through  an  opening  in  the  side  of  the  flue  or  chamber 
containing  the  gas  and  the  sample  is  withdrawn  through  it, 
usually  by  aspirator  bottles.  The  sample  should  be  taken  across 
the  whole  section  of  the  moving  gas,  the  greater  portion  from  the 
central,  or  more  rapidly  moving  part  of  the  column.  This  may  be 
accomplished  by  closing  the  inward  end  of  the  tube  and  admit- 
ting the  gas  through  perforations  along  the  side  so  spaced  that 
the  gas  will  enter  in  the  proper  proportion  at  different  points 
in  the  cross-section  of  the  flue. 

The  same  result  may  be  accomplished  by  wiring  together  a 
number  of  small  tubes  of  different  lengths  so  that  they  terminate 
at  different  points  in  the  flue.  The  end  of  the  bundle  of  tubes 
which  projects  out  of  the  flue  is  set  with  cement  in  an  iron  tube 

*  U.  S.  Bureau  of  Mines,  Technical  Paper,  25,  10. 


274  METALLURGICAL  ANALYSIS 

just  large  enough  to  receive  it.  The  iron  tube  is  connected  by 
a  reducer  to  a  rubber  tube  through  which  the  gas  is  delivered 
to  the  receiver.* 

An  iron  sampling  tube  may  be  used  for  cool  or  moderately 
warm  gases.  The  composition  of  gas  is  changed  by  contact  with 
hot  iron. 

The  water  used  in  the  aspirator  bottles  should  be  thoroughly 
shaken  with  a  quantity  of  the  gas  to  be  sampled  before  the 
sample  is  taken,  to  saturate  it  completely  with  the  several  com- 
ponent gases;  otherwise  the  composition  of  the  sample  would 
be  changed  by  the  varying  degrees  of  solublity  of  the  components. 
The  Gas  Burette.  Gas  is  measured  for  analysis  in  a  burette, 
(Fig.  97)  usually  of  100  cc.  capacity,  provided 
with  a  stopcock  and  capillary,  at  the  upper  end. 
To  dispense  with  the  necessity  of  correcting  the 
volume  of  gas  for  changes  of  temperature  while 
the  analysis  is  going  on,  due  to  changes  in 
the  temperature  of  the  surrounding  air,  the 
burette  is  enclosed  in  a  large  glass  tube  which 
is  filled  with  water  and  closed  at  each  end  with 
a  rubber  stopper,  through  which  the  burette 
projects.  The  water  in  the  tube  is  allowed  to 

1Q' attain  the  temperature  of  the  room  before  the 
Burette.  ,    .     ,       . 

analyis  begins. 

Gas  Pipettes.  A  gas  pipette  is  a  bulb  or  tube,  or  a  combina- 
tion of  these,  in  which  gaseous  mixtures  are  brought  into  con- 
tact with  absorbents.  Each  pipette  contains  an  absorbent  for 
a  single  gas  or  group  of  similar  gases  and  is  provided  with  a  capil- 
lary tubular  outlet,  through  which  the  gas  is  passed  to  the  burette 
for  measurement.  (Figs.  98  and  99.) 

Explosion  Pipette.  For  the  determination  of  methane  and 
hydrogen  a  measured  quantity  of  the  gas,  which  has  had  removed 
from  it  C02,  heavy  hydrocarbons,  62,  and  CO,  is  mixed  with 
*  A.  H.  White,  "  Gas  and  Fuel  Analysis,"  p.  10. 


GAS  ANALYSIS 


275 


an  excess  of  air  and  exploded  over  mercury  in  a  pipette  of  heavy 
glass  (Fig.  100),  provided  with  stopcocks  and  fused-in  electric 


FIG.  98.— Gas          FIG.  99.— Gas  Pipette 
Pipette  (Richards).  (Hempel). 


FIG.  100. — Explosion 
Pipette. 


terminals  for  the  passage  of  an   electric  spark  for  the  ignition 
of  the  mixture. 

The  Gases  in  Gaseous  Mixtures.     In  technical  gas  analysis  the 
following  gases  are  separated  and  measured : 

(1)  Carbon  dioxide,  C02; 

f  ethylene,  C2H4 
f  CnH2?1      |  propylene,  C3H6 

(2)  Heavy  hydrocarbons  of  1  butylene,  C4H8 

the  series  |  CnH2n_2     acetylene,  C2H2 

I  P  H       '*'  I  benzine,  CeHe 
n    2n~6  {  toluene,  C7H8* 

(3)  Oxygen,  O2;    (4)  Carbon  monoxide,  CO;    (5)  Hydrogen, 
H2;   (6)  Methane,  CH4;  and  (7)  Nitrogen,  N2. 

*  Winkler  and  Lunge,  "  Technical  Gas  Analysis,"  66. 


276  METALLURGICAL   ANALYSIS 

Absorbents.  Absorbent  for  CC>2.  Solution  of  potassium 
hydroxide.  Dissolve  250  gms.  of  commercial  potassium  hydroxide 
(KOH)  in  1  liter  of  water;  1  cc.  contains  0.21  gm.  KOH  and 
absorbs  0.083  gm.,  or  42  cc.  of  CO2.  Absorption  should  be 
complete  within  two  or  three  minutes.  This  solution  also  absorbs 
acid  fumes  if  they  are  present. 

Absorbent  for  Heavy  Hydrocarbons.  Fuming  sulphuric  acid, 
sp.gr.  1.938,  which  contains  24  per  cent  free  SOs.  Shake  the 
acid  in  the  pipette  with  the  gas  for  five  minutes. 

Absorbent  for  Oxygen.  Alkaline  solution  of  pyrogallol. 
Dissolve  250  gms.  of  KOH  in  a  liter  of  water  and  add  to  it  50 
gms.  of  CeH3(OH)3.  Agitate  the  absorbent  with  the  gas  in  the 
pipette  five  minutes.  One  cubic  centimeter  will  absorb  about 
10  cc.  of  oxygen. 

If  the  solution  is  not  fresh,  it  gives  up  CO  after  taking  up  oxygen, 
giving  incorrect  results  for  both  oxygen  and  CO. 

Yellow  phosphorus  in  sticks  may  be  used  for  the  absorp- 
tion of  oxygen,  but  under  certain  conditions  it  is  not  satisfactory.* 
Phosphorus  does  not  absorb  oxygen  readily  if  the  temperature 
is  low,  12°  to  15°  C.  or  lower;  if  the  oxygen  is  not  well  diluted 
with  nitrogen;  and  if  certain  gases  are  present,  among  the  num- 
ber being  acetylene,  ethylene,  etc. 

Absorbent  for  CO.  Cuprous  chloride  solution.  Dissolve 
250  gms.  HN4C1  in  750  cc.  of  water  in  a  bottle  provided  with  a 
rubber  stopper.  Add  200  gms.  CuCl  and  a  small  strip  of  sheet 
copper  to  prevent  oxidation  to  cupric  chloride.  For  use  in  the 
pipette,  add  50  cc.  of  ammonia  to  150  cc.  of  the  cuprous  chloride 
solution.  One  cubic  centimeter  of  this  solution  will  absorb 
16  cc.  of  CO. 

The  gas  should  be  passed  into  two  pipettes  of  this  solution 
in  succession;  the  second  one  should  contain  very  fresh  solution, 
to  effect  complete  absorption  of  all  the  CO. 

*  Winkler  and  Lunge:   "  Technical  Gas  Analysis,"  69. 


ANALYSIS   OF  A  GAS  277 

Methane  and  hydrogen  arc  best  determined  by  explosion 
over  mercury  in  an  explosion  pipette,  in  the  manner  described 
on  page  278,  and  nitrogen  is  estimated  by  difference. 

ANALYSIS  OF  A  GAS 

Measuring  the  Gas.  Set  up  the  burette  with  leveling 
tube  attached  to  its  lower  end  by  means  of  a  long  rubber  tube. 
Pour  enough  water  into  the  leveling  tube  to  bring  the  water  sur- 
face near  the  lower  end  of  the  tube  when  the  burette  is  full. 
The  water  should  be  rendered  slightly  acid  and  should  be 
saturated  with  the  gas  to  be  analyzed  before  the  analysis 
begins. 

Open  the  stopcock  of  the  burette  and  raise  the  leveling 
tube  until  the  water  fills  the  burette  and  the  capillary  from  the 
stopcock.  Close  the  stopcock.  With  a  small  rubber  tube, 
attach  the  burette  to  the  capillary  leading  to  the  aspirator  bottle, 
or  other  container  of  the  gas  to  be  analyzed.  Open  the  stop- 
cock and  lower  the  leveling  tube  to  draw  the  gas  into  the  burette. 
When  the  burette  has  been  filled,  close  the  stopcock  and  hold 
the  leveling  tube  alongside  the  burette  to  bring  the  surface  of 
the  water  in  the  burette  and  in  the  leveling  tube  to  the  same 
level.  Read  the  burette. 

CO2  in  Gas.  Fill  the  bulb  of  the  pipette  and  its  capillary  tube 
with  the  absorbent.  Attach  the  pipette  to  the  burette  with 
a  small  rubber  tube,  open  the  stopcock,  and  raise  the  leveling 
tube  to  drive  the  gas  into  the  pipette.  When  all  the  gas  has  been 
driven  over  and  the  water  of  the  burette  fills  the  capillary  of 
the  pipette,  close  the  stopcock  and  shake  the  pipette  carefully 
for  four  or  five  minutes.  Open  the  stopcock,  lower  the  leveling 
tube,  and  draw  the  gas  into  the  burette  until  the  absorbent  in 
the  pipette  approaches  the  stopcock.  Close  the  stopcock, 
bring  the  water  in  the  burette  and  leveling  tube  to  the  same 
level,  and  read  the  burette.  The  loss  in  volume  represents 


278  METALLURGICAL  ANALYSIS 

the  C(>2  and  this  divided  by  the  original  volume  gives  the  per- 
centage of  C02  in  the  gas. 

Heavy  Hydrocarbons  in  Gas.  After  the  absorption  of  the 
C02,  pass  the  remaining  volume  of  gas  from  the  burette  into 
the  pipette  containing  the  absorbent  of  heavy  hydrocarbons 
and  agitate  the  pipette  about  five  minutes.  Return  the  gas  to 
the  burette  and,  since  it  may  contain  fumes  of  sulphuric  acid, 
it  should  be  passed  into  the  KOH  pipette,  shaken,  and  returned 
to  the  burette  before  the  volume  is  read.  The  decrease  in 
volume  represents  the  heavy  hydrocarbons. 

Oxygen  in  Gas.  After  the  determination  of  heavy  hydro- 
carbons, pass  the  remaining  gaseous  mixture  into  the  pipette 
for  the  absorption  of  oxygen  in  the  manner  described  above  for 
the  determination  of  CCb,  and,  after  agitation,  return  the  remain- 
ing gas  to  the  burette  and  note  the  diminution  in  volume,  which 
represents  the  oxygen  in  the  gas. 

The  absorbent  must  be  frequently  renewed.  See  note  under  absorb- 
ent for  oxygen. 

CO  in  Gas.  Pass  the  gas  next  into  the  first  absorption 
pipette  for  CO  and,  after  agitation,  pass  it  into  the  second  pipette 
for  CO  containing  fresh  ammoniacal  cuprous  chloride  solution, 
and,  finally,  return  the  remaining  gas  to  the  burette  and  read 
its  volume  for  the  estimation  of  CO. 

Nitrogen  in  Gas.  If  the  gaseous  mixture  contains  no 
hydrogen  or  methane,  the  volume  in  the  burette,  after  the 
absorption  of  CO,  is  read  and  recorded  as  nitrogen. 

H  and  CH4  in  Gas.  If  the  gaseous  mixture  contains  either 
or  both  of  these  gases,  after  the  CO  has  been  determined,  a 
suitable  volume — 10  to  15  cc. — of  the  remaining  gas  is  measured 
in  the  burette,  the  stopcock  closed,  the  leveling  tube  lowered, 
and  the  stopcock  opened  to  admit  60  cc.  to  70  cc.  of  air;  the 
quantity  must  be  sufficient  to  furnish  more  than  enough  oxygen 
to  combine  with  the  hydrogen  and  methane  present.  The  vol- 


ANALYSIS  OF  A  GAS 


279 


ume  of  the  total  mixture  is  read;  it  is  passed  into  an  explosion 
pipette  containing  mercury  and  is  exploded  by  passing  an  electric 
spark  through  it. 


2H2+O2   =  2H2O. 

One  volume  of  CH4  combines  with  two  volumes  of  oxygen 
to  form  one  volume  of  CO2  and  two  volumes  of  water  (in  the 
gaseous  form),  but  the  water  ,  condenses,  leaving  only  the  one 
volume  of  C02. 

The  free  hydrogen  combines  with  oxygen  in  the  proportion 
of  two  volumes  of  the  former  to  one  of  the  latter,  the  three 
disappearing  when  the  resulting  water  condenses. 

Pass  the  gas  back  into  the  burette  and  read  its  volume. 
Note  the  diminution  in  volume  owing  to  the  formation  of  water. 

Pass  the  gas  now  into  the  C02  pipette,  agitate,  return  the 
gas  to  the  burette,  and  read  its  volume.  This  diminution  in 
volume  is  due  to  absorption  of  C02  formed  from  the  methane 
and  is  equal  to  the  volume  of  the  methane.  Twice  the  volume 
of  the  methane  represents  the  volume  of  oxygen  withdrawn  from 
the  mixture  by  the  hydrogen  of  the  methane.  The  remaining 
diminution  of  volume,  owing  to  the  formation  of  water,  is  due  to 
the  burning  of  the  free  hydrogen,  and  two-thirds  of  this  reduction 
represents  the  volume  of  hydrogen. 


Example. 

Readings  of 
Burette. 

Volume  of 
Gas. 
cc. 

Sample  of  gas  taken    

98  8 

98  8 

After  absorption  of  COz 

97  2 

Volume  of  CO2.          

1  6 

After  absorption  of  heavy  hydrocarbons  

93  4 

Volume  of  heavy  hydrocarbons. 

3  8 

After  absorption  of  oxygen  ...    . 

93  0 

Volume  of  oxygen             .  . 

0  4 

After  absorption  of  CO.    ... 

84  2 

Volume  of  CO  

8  8 

280 


METALLURGICAL  ANALYSIS 


Example. 

Readings  of 
Burette. 

Volume  of 
Gas. 
cc. 

Retained  in  the  burette  for  determination  of  CH4 
and  H2                                    

12  4 

Air  drawn  in  for  explosion  mixture 

96  4 

After  explosion  and  cooling                       .          .  . 

74  8 

Contraction  due  to  formation  of  H2O  
After  absorption  of  CO2  resulting  from  CH4. 

68  0 

21.6 

Volume  of  CH4                                          

6  8 

Contraction  due  to  withdrawal  of  O2  to  combine 
with  CH4  to  form  H2O  (2  X6.8) 

13.6 

Contraction  due  to  H2O  formed  from  free  H2  and  O 
(216-13.6)                  

8.0 

Contraction  due  to  H2  (f  X8)  

5.3 

(£>   0  -y  OA    9\ 
^—  ——  —  )    

.     /5.3X84.2\ 

46.2 

QC     A 

The  composition  of  the  gaseous  mixture  is  therefore  as  follows: 

CO2 1.6 

Heavy  hydrocarbons 3.8 


02.. 
CO. 
CH4 
H2.. 

N2., 


0.4 

8.9 

46.7 

36.4 

2.0 


EXPLOSION  METHOD  FOR  CARBON  MONOXIDE, 
METHANE,  AND  HYDROGEN 

In  the  laboratories  of  the  United  States  Steel  Corporation  * 
CO,  CH4,  and  H2  are  determined  as  follows: 

Explode  a  sample  of  the  gas  with  a  known  quantity  of  a 
definite  mixture  of  nitrogen  and  oxygen ;  note  the  contraction  (I) . 
Pass  the  gas  into  a  KOH  pipette  to  absorb  the  CO2  and  measure 
*  Met.  and  Chem.  Eng.,  9,  302  and  356. 


CARBON  MONOXIDE,  METHANE,  AND  HYDROGEN     281 

the  residue;  note  the  contraction  (II).     Add  a  definite  volume  of 
hydrogen  (sufficient  to    combine  with  all   the   remaining  02  as 
H20)  and  explode  with  an  electric  spark.     Measure  the  residue 
of  nitrogen  and  hydrogen  and  note  the  contraction  (III). 
From  these  data  taken  in  conjunction  with  the  reactions, 

2CO+02  =  2C02 
2H2+02  =  2H2O 
CH4+2O2  =  CO2+2H2O, 

the  following  equations  are  formed : 

Contraction  I  =  |  carbon  monoxide+f  hydrogen+2  methane. 

Carbon  dioxide  formed  =  carbon  monoxide + methane. 

Oxygen  consumed  =  f  carbon  monoxide +J  hydrogen+2 
methane. 

From  these  equations  the  following  formulae  for  calculating 
the  components  of  the  original  sample  are  derived: 

Oxygen  consumed  =  oxygen  added  —  J  Contraction  III. 

Hydrogen  =  Contraction  I  — oxygen  consumed. 

Carbon  monoxide 

_ Con.  I+(4XCon.  II)+Con.  Ill-oxygen  added 

3 

Methane  =  Contraction  II  —  carbon  monoxide  present. 
The  Orsat  Apparatus.  This  is  a  compact  arrangement  of 
a  gas  burette,  absorption  pipettes,  etc.,  in  a  portable  case 
(Fig.  101).  The  burette  is  attached  permanently  to  the  pipettes 
with  capillary  tubing  provided  with  the  necessary  stopcocks. 
The  manipulation  in  the  process  of  analysis  is  practically  the 
same  as  that  described  on  page  277. 

Many  modifications  of  the  original  Orsat  apparatus  have 
been  described.  Among  them  may  be  mentioned  those  of 
Allen  and  Moyer,*  Williams,  f  and  Burrel.t 

*  Trans.  Amer.  Soc.  Mech.  Eng.,  18,  901. 

f  Jour,  of  Ind.  and  Eng.  Chem.,  4,  387  (1911). 

|  Jour,  of  Ind.  and  Eng.  Chem.,  4,  297  (1911). 


282 


METALLURGICAL  ANALYSIS 


Automatic  Analysis  of  Gas.     Apparatus  of  various  types  are 
in  use  for  measuring  and  recording  mechanically  the  percentage 
of   a   single   gas  in  a   gaseous   mixture. 
They  have  been  adapted  to  the  estima- 
tion of  C02,  SO2,  HC1,  and  C12. 

In  the  Simmance-Abady  Automatic 
Gas  Analyzer  (Fig.  102)*  the  gas  is 
drawn  into  a  bulb  in  measured  portions 
from  the  flue,  from  which  it  is  forced 
through  an  absorbent  into  a  second  bulb 
which  rises  to  a  point  on  a  scale  indi- 
cating the  volume  of  gas  that  has  been 
absorbed.  A  pen  records  the  percentage 
on  a  chart  actuated  by  a  clock,  and  the 
gas  is  automatically  discharged  as  the 
bulb  descends  in  position  to  receive  the 
succeeding  sample. 

The  Uehling  carbon    dioxide    meter 


FIG.  101.— Orsat 
Apparatus. 


FIG.  102. — Simmance-Abady 
Automatic  Gas  Analyzer. 


*  Met.  and  Chem.  Eng.,  9,  327,  and  10,  121. 


CALORIFC   POWER  OF  GAS 


283 


(Fig.  103)*  measures  and  records  the  drop  in  pressure  between 
the  orifices  of  admission  and  exit  to  the  absorbent  chamber. 

With  this  instrument  the  per  cent  of  CO2  may  be  indicated 
at  the  boiler  front  and  a  continuous  record  made  elsewhere 
at  the  same  time,  of  both  the  CC>2  and 
the  temperature. 

Calorific  Power  of  Gas.  The  calo- 
rific power  of  gas  is  usually  determined 
in  a  calorimeter  of  the  Junkers  type 
(Fig.  104). 


FIG.  103. — Uehling  Carbon 
Dioxide  Meter. 


FIG.  104. — Junkers  Gas 
Calorimeter. 


A  definite  volume  of  the  gas  is  burnt  in  a  Bunsen  burner, 
at  a  uniform  rate,  the  flame  being  surrounded  by  a  jacket', 
through  which  water  flows  at  a  rate  regulated  so  as  to  absorb  all 
the  heat  of  the  flame.  A  thermometer  is  fixed  in  the  stream 
of  water  at  its  inlet  and  one  at  the  outlet. 

To  make  a  test,  the  gas  is  ignited  and,  while  it  is  burning 
at  a  definite  and  uniform  rate  shown  by  the  meter,  and  the 
*  Met.  and  Chem.  Eng.,  9,  329,  and  10,  497. 


284  METALLURGICAL  ANALYSIS 

water  is  flowing  uniformly  through  the  calorimeter,  the  two 
thermometers  are  observed  until  the  readings  have  become  con- 
stant. When  the  hand  of  the  meter  passes  a  certain  point, 
the  zero,  for  instance,  the  tube  through  which  the  water  flows 
from  the  calorimeter  is  quickly  turned  to  deliver  the  water  to  a 
receiver,  where  it  is  allowed  to  collect  until  the  hand  of  the  meter 
returns  to  the  point  selected  for  the  beginning  of  the  test.  The 
thermometers  are  to  be  read  frequently  to  see  if  they  remain 
constant.  If  they  do  not,  the  readings  are  to  be  averaged. 
The  water  is  then  weighed  and  its  weight  multiplied  by  the 
difference  in  temperature  between  the  inflowing  and  the  out- 
flowing water.  This  gives  the  quantity  of  heat  produced  by  the 
gas  that  was  burnt  while  the  water  was  being  collected.  In 
order  that  tests  may  be  comparable,  one  with  another,  it  is  nec- 
essary in  each  test  to  correct  the  volume  of  the  gas  for  tem- 
perature and  pressure  to  a  uniform  standard;  usually,  when 
English  units  are  used,  to  60°  F.  and  30  ins.  of  mercury.  In 
the  laboratories  of  the  United  States  Steel  Corporation,  62°  F. 
and  30  ins.  of  mercury  have  been  adopted  as  the  standard.  A 
table  for  reducing  volumes  of  gas  to  this  standard  is  given  on 
page  330.*  At  the  time  a  test  is  made,  a  thermometer  and 
barometer  are  read  which  give  the  conditions  under  which  the 
gas  is  burned.  The  measured  volume  of  gas  is  then  reduced  to 
standard  conditions  (usually  expressed  in  cubic  feet)  and  the 
total  heat  produced,  divided  by  this  corrected  volume,  gives  the 
heating  power  in  British  thermal  units  if  English  units  have  been 
used  throughout,  and  in  calories  if  15°  C.  and  760  mm.  of  mer- 
cury are  taken  as  the  standard,  and  the  gram  and  centimeter 
as  the  units. 

Automatic    Recording    Gas    Calorimeter.     If    the   water    is 

made  to  flow  into  a  calorimeter  at  a  constant  temperature  and 

uniform  rate,  and  the  gas  is  burnt  at  a  constant  rate,  then  any 

change  in  the  heating  value  of  the  gas  will  be  expressed  by  a  change 

*  Met.  and  Chem.,  Eng.,  9,  358. 


CALORIFIC  POWER  OF  A  GAS   FROM  ITS  ANALYSIS     285 

in  temperature  of  the  water  flowing  from  the  calorimeter.  A 
calorimeter,  then,  which  has  a  self-registering  thermometer  to 
record  continuously  the  temperature  of  the  outflowing  water 
becomes  a  self-registering  calorimeter. 

CALCULATION  OF  THE  CALORIFIC  POWER  OF  A 
GAS  FROM  ITS  ANALYSIS 

The  heating  value  of  a  gas  may  be  calculated  with  a  fair 
degree  of  accuracy  from  its  analysis,  if,  in  addition  to  the  H2, 
CHi,  and  CO,  the  components  of  the  heavy  hydrocarbons 
are  identified  and  the  quantity  of  each  determined.  This  presents 
no  difficulty  with  blast-furnace  gas  which  is  devoid  of  heavy 
hydrocarbons,  and  little  difficulty  is  experienced  with  producer 
gas  and  natural  gas,  since  the  former  usually  contains  only  a 
very  small  quantity  of  such,  and  that  is  ethylene,  C2H4,  and 
the  latter  is  composed  chiefly  of  methane,  CELi,  and  ethane, 


The  quantity  of  each  combustible  component  in  a  cubic 
foot  of  the  mixture  is  multiplied  by  its  heating  value  and  the 
sum  taken  as  the  calorific  power  of  the  gas.  The  heating  values 
of  these  gases  are  given  below  in  B.t.u.'s  per  cubic  foot  at  62°  F. 
and  a  pressure  of  30  ins.  of  mercury,  based  on  Earnshaw's 
calculations.* 

B.  t.  u.'s  per 

cu.  ft.  at  62°  and 

30"  mercury. 

Hydrogen,  H2  ..................  .  .......  325.0 

Methane,  CH4  .........................  1005.3 

Carbon  monoxide,  CO  ...................  322.2 

Ethylene,  C2H4  ........................  1581.9 

Ethane,  C2H6  ..........................  1757.6 

*  Jour.  Franklin  Inst.,  146,  161. 


286  METALLURGICAL  ANALYSIS 


ANALYSIS   OF   CLAY 

The  Sample.  Clays  should  be  sampled  and  the  sample 
prepared  for  analysis  according  to  the  method  described  for 
sampling  limestone,  page  160.  The  clay  must  be  dried  before 
grinding. 

Moisture.  Weigh  1  gm.  of  the  sample,  transfer  it  to  a  30- 
gm.  platinum  crucible,  heat  at  110°  C,  for  an  hour,  cool  in  a 
desiccator  and  weigh.  The  loss  in  weight  represents  the  moisture. 

Combined  water  is  best  determined  with  the  bulb  tube  (method 
of  Brush  and  Penfield)  described  on  page  49. 

Loss  on  Ignition.  Weigh  1  gm.,  transfer  it  to  a  30-gm. 
platinum  crucible,  cover,  and  heat  with  a  blast  lamp  thirty 
minutes,  cool  in  a  desiccator  and  weigh.  The  loss  in  weight 
is  reported  as  the  loss  on  ignition. 

SiO2.  To  1  gm.  of  the  sample  in  a  30-gm.  platinum  crucible 
(or  to  the  residue  after  the  determination  of  moisture  or  loss  on 
ignition)  add  6  gms.  of  dry  sodium  carbonate,  fuse,  and  com- 
plete the  determination  according  to  the  method  for  8162  on 
page  71. 

Fe2Os.  To  the  filtrate  from  the  Si02  (above)  add  ammonia 
to  precipitate  the  hydroxides  of  iron,  aluminum,  etc.  Filter, 
wash  the  precipitate  into  a  beaker  (see  p.  61),  dissolve  it  in 
sulphuric  acid,  reduce  the  iron  with  zinc  to  the  ferrous  condition, 
and  titrate  it  with  standard  potassium  permanganate  solution 
(see  p.  55) ;  or  the  precipitate  may  be  dissolved  in  hydrochloric 
acid  and  titrated  with  standard  potassium  dichromate  solution 
after  reduction  with  stannous  chloride  (see  p.  62).  If  the  latter 
method  is  used,  see  note  in  regard  to  effect  of  platinum  (p.  63). 

CaO.  To  the  filtrate  from  the  precipitate  of  iron  and 
aluminum  hydroxides  add  ammonium  oxalate  and  complete 
the  determination  according  to  the  method  described  on  page 
162. 

MgO.     Precipitate  the  magnesium  as  magnesium  ammonium 


ALKALIES   IN   CLAY 


287 


phosphate  and  proceed  according  to  the  method  for  the  determi- 
nation of  magnesia  in  limestone,  page  165. 

A^Oa.     Weigh  a  separate  portion  and  proceed  according  to 
the  method  (phosphate)  described  on  page  87. 


ALKALIES  IN  CLAY 
J.  LAWRENCE  SMITH  METHOD  * 

Reagents.     Pure  dry  ammonium  chloride,  NH4C1. 

Pure  calcium  carbonate,  CaCOs. 

Ammonium  carbonate,  (NH^COs. 

Ammonium  oxalate  solution.     Dissolve  40  gms.   (N £[4)20204 
+2H20  in  1  liter  of  water. 

Alcohol,  80  per  cent  strength. 

Solution  of  chlorplatinic  acid. 

Weigh  1  gm.  of  the  clay  and  transfer 
it  to  an  agate  mortar;  add  1  gm.  of 
ammonium  chloride  and  grind  well  to 
mix.  Add  nearly  all  of  8  gms.  of  calcium 
carbonate  and  grind. 

Place  a  little  calcium  carbonate  in  a 
large  platinum  crucible,  or  better,  in  a 
long  narrow  crucible  with  close  fitting 

cap,  designed  for  the  purpose  (Fig.  106). 

r~,          ,  .  FIG.  105. — Lawrence  Smith 

The  calcmm  carbonate  prevents  the  sm-      Crudble  for  Alkali  De_ 

tered  cake  from  sticking,  f  termination. 

Transfer  the  charge  from  the  agate 

mortar  to  the  crucible.  Grind  the  remaining  part  of  the 
8  gms.  of  calcium  carbonate  in  the  mortar  to  clean  out  the 
charge,  and  add  it  to  the  crucible.  Put  on  the  cover  and  heat 

*Amer.   Jour.   Sci.,   Second  Series,   50,   269    (1871).     Hillebrand,   Bull. 
422,  U.  S.  Geological  Survey,  p.  171  (1910). 
t  Schaller,  Bull.  U.  S.  G.  S.,  422,  173. 


288  METALLURGICAL  ANALYSIS 

gently  the  lower  two-fifths  of  the  crucible,  keeping  the  top  cool 
to  prevent  loss  by  volatilization  of  the  alkaline  chlorides  formed. 

If  an  ordinary  crucible  is  used,  let  it  project  through  a  hole 
in  an  asbestos  board  (see  Fig.  58,  p.  74)  to  protect  the  top 
from  the  heat  of  the  flame. 

Keep  the  heat  low  for  about  ten  minutes  until  the  odor 
of  ammonia  no  longer  comes  from  the  crucible,  then  heat  the 
lower  part  of  the  crucible  to  redness  and  continue  the  heating 
at  that  temperature  for  about  forty-five  minutes. 

This  converts  the  alkalies,  and  much  of  the  calcium,  to  chlorides. 

Transfer  the  sintered  cake  to  a  platinum  dish,  and  add  1  or 
2  cc.  of  hot  water.*  When  the  cake  is  slaked,  add  hot  water 
and  stir  to  disintegrate  thoroughly.  Filter  and  wash  by  decanta- 
tion  and  finally  wash  thoroughly  on  the  filter  with  hot  water. 

Add  to  the  filtrate  ammonia  and  about  1.5  gm.  ammonium 
carbonate,  which  will  precipitate  nearly  all  the  calcium. 

CaCl»-KNH4)sCO8=CaCO,+2NH4Cl. 

Filter  and  wash.  Evaporate  the  filtrate  to  dryness  in  a  plat- 
inum dish  and  carefully  heat  to  dull  redness  to  drive  off  salts 
of  ammonia. 

The  dish  should  be  fitted  into  a  hole  in  an  asbestos  board  to  prevent 
the  admission  of  sulphur  to  the  solution  from  the  gas  flame. 

Dissolve  the  alkaline  chlorides  in  a  very  little  water. 

If  the  sample  contains  sulphur  or  if  sulphur  has  been  intro- 
duced from  the  flame,  add  a  drop  of  BaCb  solution.  Then  add 
a  little  ammonium  carbonate  solution  to  precipitate  the  remain- 
ing Ba,  and  finally,  add  a  little  ammonium  oxalate  solution 
to  precipitate  the  remaining  calcium.  Filter  into  a  platinum 
crucible  and  evaporate  the  filtrate  to  dryness,  taking  precau- 
tions in  regard  to  the  introduction  of  sulphur  from  the  flame. 

*  Steiger,  loc.  cit,  173. 


ALKALIES  IN  CLAY  289 

Cool  in  a  desiccator  and  weigh.  Dissolve  in  a  little  water  and, 
if  there  is  an  insoluble  residue,  filter  into  a  small  porcelain  dish, 
wash,  ignite  the  paper  with  the  residue,  cool,  weigh,  and  deduct 
from  the  previous  weight.  The  difference  represents  the  com- 
bined weight  of  potassium  and  sodium  chlorides. 

K2O.  To  the  solution  of  the  chlorides  in  the  porcelain  dish 
add  an  excess  of  a  solution  of  chlorplatinic  acid. 

Any  precipitate  which  forms  should  dissolve  when  heated  on  the 
water-bath. 

Evaporate  the  solution  until  the  residue  solidifies  on  cooling 
Now  treat  the  mass  with  80  per  cent  alcohol,  filter  through  a  very 
small  filter,  and  wash  by  decantation  with  more  of  the  alcohol, 
retaining  as  much  as  possible  of  the  precipitate  in  the  dish. 

Dry  the  dish  and  filter  a  few  minutes  to  drive  off  the  alcohol. 
Transfer  the  precipitate  to  a  weighed  platinum  crucible.  Dis- 
solve with  hot  water  any  precipitate  that  adheres  to  the  dish 
and  wash  it  through  the  filter  into  the  crucible. 

Evaporate  the  solution  to  dryness  on  a  water-bath,  cover 
the  crucible  to  prevent  loss  by  decrepitation  and  heat  to  135°  C. 
Cool  in  a  desiccator  and  weigh  K2PtCl6.  The  factor  for  KC1 
in  K2PtCl2  is  0.30674  and  the  factor  for  K2O  in  K2PtCl6  is 
0.19376. 

Na2O.  Deduct  the  weight  of  KC1  from  the  combined  weight 
of  KC1  and  NaCl  and  multiply  the  difference  by  the  factor  for 
Na20  in  NaCl,  which  is  0.53028. 

The  sodium  may  be  determined  directly  from  the  filtrate  from 
the  potassium  platinic  chloride  by  evaporating  the  solution 
and  precipitating  the  platinum  with  H2S,  filtering  and  evaporat- 
ing the  filtrate  to  dryness  and  weighing  as  NaCl. 


290  METALLURGICAL  ANALYSIS 


METHODS    FOR    THE    DETERMINATION  OF  SOME  OF 
THE  MINOR  METALS 

CHROMIUM  * 

Weigh  1  gm.  of  the  sample,  which  must  be  ground  extremely 
fine,  and  fuse  it  one  hour  in  a  platinum  crucible  with  about  10 
gms.  of  a  basic  mixture  composed  of  4  parts  of  lime  or  magnesia 
and  1  part  each  of  potassium  and  sodium  carbonates.  Transfer 
the  sintered  mass  to  a  beaker  and  dissolve  it  in  water  and  sul- 
phuric acid. 

If  any  black  particles  remain  undissolved,  filter  them  off 
and  fuse  them  again  with  the  basic  mixture;  dissolve  and  add 
to  the  first  solution.  Add  an  excess  of  standard  ferrous  ammo- 
nium sulphate  solution,  accurately  measured,  and  titrate  the 
excess  with  standard  potassium  permanganate  solution.  (See 
p.  141.) 

NICKEL  AND  COBALT 

Add  to  1  gm.  of  the  sample  in  a  200-cc.  Erlenmeyer  flask 
15  cc.  of  NHOs  and  boil  until  the  solution  becomes  syrupy. 
Add  10  cc.  NHOs  and  5  gms.  KClOs  and  boil  ten  minutes.  Add 
5  cc.  more  of  HNOs  and  5  gms.  KClOs  and  boil  until  yellow 
fumes  are  no  longer  produced.  Cool,  add  40  cc.  of  hot  water, 
filter,  and  wash.  Reserve  the  filtrate  (a).  Wash  into  the  flask 
the  residue  on  the  filter.  Place  the  flask  under  the  funnel  and 
pour  through  the  filter  15  cc.  of  warm  dilute  hydrochloric  acid 
(1:2)  and  wash  with  a  little  hot  water.  Heat  the  flask  to 
dissolve  the  residue.  Add  20  cc.  bromine  water  and  an  excess 
of  ammonia.  Boil,  let  the  precipitate  settle,  filter,  and  wash 
with  hot  water.  Combine  this  filtrate  with  the  filtrate  (a), 
and  boil  off  the  excess  of  ammonia.  Neutralize  the  solution 
with  hydrochloric  acid  and  add  10  cc.  in  excess.  Boil,  dilute 
*  Sutton,  "Volumetric  Analysis,"  p.  182. 


NICKEL  AND  COBALT  291 

to  300  cc.  and  saturate  the  solution  with  hydrogen  sulphide 
by  passing  through  it  a  current  of  the  gas.  Filter  and  wash 
the  precipitate  with  dilute  hydrogen  sulphide  water.  Boil 
the  solution  down  to  about  25  cc.  and  add  NaOH  to  neu- 
tralize the  acid.  Pour  this  solution,  which  contains  the  nickel, 
cobalt,  and  zinc,  slowly  into  50  cc.  of  a  10  per  cent  solution 
of  sodium  hydroxide,  stirring  constantly.  Dilute  the  solution 
with  an  equal  volume  of  water  and  filter.  Dissolve  the  pre- 
cipitate in  a  little  hydrochloric  acid,  nearly  neutralize  with 
sodium  hydroxide,  and  pour  again  into  a  10  per^cent  solu- 
tion of  sodium  hydroxide,  stirring.  Dilute  and  filter.  Dis- 
solve the  hydroxides  of  nickel  and  cobalt,  in  a  little  dilute 
£[2804;  wash  the  filter  free  from  acid.  Dilute  the  filtrate  to 
125  cc.,  add  5  gms.  ammonium  sulphate  and  40  cc.  of  ammonia. 
Electrolyze  several  hours  with  a  current  of  Dioo  =  0.5  to  0.7  am- 
peres and  2.8  to  3.3  volts. 

When  precipitation  is  complete,  a  few  drops  on  a  porcelain 
plate  with  ammonium  sulphide  should  show  no  trace  of  black 
color. 

With  rotating  anode  or  cathode  the  current  may  be  increased 
to  Dioo  =  4  amperes  and  5.5  volts  and  the  time  of  deposition 
thereby  shortened  to  about  half  an  hour. 

Ni.  After  weighing,  dissolve  the  nickel  and  cobalt  in  nitric 
acid.  Add  hydrochloric  acid  and  boil  the  solution  down  to 
convert  nitrates  to  chlorides.  Dilute  so  that  there  will  be  not 
more  than  0.1  gm.  cobalt  per  100  cc.  to  prevent  solution  of 
the  precipitate.*  Heat  to  boiling,  precipitate  the  nickel  with 
dimethylglyoxime,  and  complete  the  determination  according  to 
the  method  on  page  140. 

Co.  When  the  nickel  has  been  determined  by  the  dimethyl- 
gloxime  method,  deduct  its  weight  from  the  combined  weight 
of  nickel  and  cobalt  and  calculate  the  percentage  of  Co. 

*  Trice  and  Meade;  "  Brass  Analysis/'  p.  115. 


292  METALLURGICAL  ANALYSIS 

CADMIUM 
METHOD  OF  BEILSTEIN  AND  JAWEIN  * 

Add  10  cc.  of  nitric  acid  to  0.5  gm.  of  the  ore  in  a  250-cc. 
Erlenmeyer  flask.  Boil  down  to  about  5  cc.,  add  7  cc.  of  sul- 
phuric acid  and  boil  over  a  free  flame  to  dense  fumes  of  sul- 
phuric acid.  Cool,  add  25  cc.  of  water,  heat  to  boiling,  and  let 
it  stand  hot  to  dissolve  iron  sulphate.  Cool,  filter,  and  wash 
with  dilute  sulphuric  acid  (1:1).  Dilute  the  filtrate  to  200 
cc.  and  pass  through  it  a  current  of  hydrogen  sulphide.  Filter 
and  wash  with  dilute  hydrogen  sulphide  water  acidulated  with 
hydrochloric  acid.  Wash  the  precipitate  into  a  beaker,  using 
as  little  water  as  possible.  Place  the  beaker  under  the  funnel 
and  pour  through  the  filter  a  strong  cold  solution  of  potassium 
cyanide.  Use  as  little  potassium  cyanide  solution  as  possible 
to  dissolve  the  sulphides  of  copper,  etc.,  that  may  be  present  and 
leave  the  yellow  or  orange  sulphide  of  cadmium.  Filter  through 
the  same  paper  and  wash  with  dilute  hydrogen  sulphide  water. 
Dissolve  the  cadmium  sulphide  on  the  filter  with  as  little  hot 
dilute  hydrochloric  acid  (1  :  1)  as  possible.  Add  5  cc.  of  sul- 
phuric acid  and  boil  to  white  fumes.  Cool  and  dilute  to  20  cc. 
Add  a  drop  of  phenolphthalein  solution  and  then  add  pure  sodium 
hydroxide  solution  until  a  permanent  red  color  is  produced. 
Stir  and  add  a  solution  of  potassium  cyanide  slowly,  until  the 
cadmium  hydroxide  dissolves,  being  very  careful  not  to  add  an 
excess.  Dilute  to  a  volume  of  100  to  150  cc.  and  electrolyze 
in  the  cold  five  to  six  hours  with  a  current  of  Dioo  =  0.5  to  0.7 
amperes  and  4.8  to  5  volts.  After  the  expiration  of  this  time, 
increase  the  current  to  about  1  or  1.2  amperes  and  continue 
the  electrolysis  one  hour  more.  Wash  the  cathode  successively 
with  water,  alcohol,  and  ether.  Dry  and  weigh. 

*  Berichte,  12,  466,  through  Treadwell-Hall,  "  Analytical  Chemistry,"  Vol. 
2,  150. 


MERCURY  293 

If  the  stronger  current  is  run  from  the  beginning,  the  metal  will 
be  spongy;  if  the  weaker  current  is  continued,  more  than  twelve  hours 
will  be  required  for  total  precipitation. 


MERCURY  * 

Treat  1  gm.  of  the  ore  with  15  cc.  of  nitric  acid  and  10  cc. 
of  hydrochloric  acid  at  a  gentle  heat  until  the  ore  is  decomposed. 

Add  more  nitric  acid  if  necessary,  but  do  not  evaporate  to 
too  small  a  volume,  since  there  is  danger  of  volatilizing  some 
mercuric  chloride.  Filter  into  an  Erlenmeyer  flask  and  wash. 
Nearly  neutralize  the  filtrate  with  sodium  carbonate  and  add  a 
slight  excess  of  freshly  prepared  ammonium  sulphide.  Shake 
the  flask  to  rotate  the  solution  and  add  a  solution  of  pure  sodium 
hydroxide  until  the  dark  liquid  begins  to  clear.  Heat  to  boil- 
ing and  add  more  NaOH  until  the  solution  is  perfectly  clear. 
The  mercury  is  now  in  solution  as  Hg(SNa)2.  If  any  precipitate 
forms,  filter;  precipitate  the  mercury  from  the  filtrate  by  adding 
ammonium  nitrate.  Boil  until  the  odor  of  ammonia  is  very 
faint. 

Let  the  precipitate  settle. 

Hg(SNa)2+2NH4N03  =2NaN03+  (NH4)2S+HgS. 

If  any  free  sulphur  has  precipitated  with  the  sulphide  of 
mercury,  before  filtering,  boil  with  a  little  sodium  sulphite  to 
remove  the  sulphur. 

Na2S03+S=Na2S203; 

The  sulphur  may  be  dissolved  from  the  precipitate  with 
carbon  disulphide  after  filtering.  Filter  in  a  Gooch  crucible 
and  wash  by  decantation  with  hot  water  until  the  washings 
do  not  react  with  silver  nitrate  solution.  Transfer  the  pre- 
cipitate to  the  crucible,  dry  at  110°  C.  and  weigh  as  HgS. 

*  Treadwell-Hall,  "  Analytical  Chemistry,"  2,  134. 


294  METALLURGICAL  ANALYSIS 

TIN 

If  the  ore  is  practically  pure  cassiterite  the  metallic  tin  may 
be  reduced  and  recovered  in  a  suitable  bead  for  weighing  by 
fusing  the  finely  ground  ore  with  potassium  cyanide  in  a  por- 
celain crucible.  The  fused  mass,  after  cooling,  is  dissolved  in 
water,  and  the  metallic  tin  is  dried  and  weighed. 

If  the  ore  is  impure,  other  metals  may  be  reduced  with  the 
tin,  and  if  silica  is  present,  some  of  the  tin  will  combine  with  it 
and  go  into  the  slag. 

The  following  method  by  Milon  and  Fouret  *  is  recommended. 

Sn  in  Ore.  Mix  2  gms.  of  the  finely  ground  sample  with 
20  gms.  of  sodium  dioxide  in  a  6-cm.  sheet-iron  crucible.  Fuse 
carefully  twenty  minutes,  cool  and  place  in  a  500-cc.  beaker 
with  150  cc.  of  water.  Cover  with  a  watch  glass  and  when 
the  action  becomes  quiet,  add,  a  little  at  a  time,  70  cc.  of  hydro- 
chloric acid.  When  the  mass  is  decomposed  take  out  the  crucible 
and  wash  it  off.  Heat  the  solution  to  60°  C.  and  add  4  gms. 
of  iron  filings  to  precipitate  arsenic,  antimony,  and  copper, 
and  to  reduce  the  stannic  to  stannous  chloride.  This  operation 
requires  about  half  an  hour. 

Filter  into  a  500-cc.  Erlenmeyer  flask  and  wash  the  residue 
well  with  hot  water.  Heat  the  filtrate  to  95°  C.  and  add  10 
gms.  of  pure  zinc  to  precipitate  the  tin.  Drops  of  the  solution 
should  be  tested  from  time  to  time  on  a  porcelain  plate  with 
hydrogen  sulphide  water.  A  brown  precipitate  indicates  that 
tin  is  still  in  solution. 

When  the  tin  is  all  precipitated,  decant  the  solution  through 
a  funnel  containing  a  plug  of  glass  wool,  leaving  most  of  the 
tin  and  the  zinc  in  the  flask.  Put  the  glass  wool  with  the  tin, 
which  was  carried  over,  into  the  flask.  Fit  the  flask  with  a 
two-hole  rubber  stopper  carrying  glass  tubes  for  the  passage 
of  CO2.  Pass  CO2  through  the  flask  several  minutes.  Remove 
*  Eighth  International  Congress  of  Applied  Chemistry,  1,  373. 


TIN  295 

the  stopper  and  pour  into  the  flask  30  cc.  of  hydrochloric  acid. 
Replace  the  stopper  and  warm  the  flask  gently  until  the  tin 
and  zinc  are  completely  dissolved.  Close  the  exit  tube  and  cool 
the  flask.  When  cold,  disconnect  the  CO2  generator,  remove 
the  stopper  and  wash  off  the  tubes  with  water  from  which 
the  air  has  been  expelled  by  CO2  (1  liter  of  water  +3  gms. 
NaHCOs+HCl),  dilute  the  solution  to  250  cc.  with  the  same 
water,  add  a  few  drops  of  starch  solution,  and  titrate  with 
standard  iodine  solution. 

Low  *  fuses  0.5  gm.  of  the  ore  mixed  with  a  little  charcoal 
in  an  iron  crucible  with  sodium  hydroxide,  dissolves  in  hydro- 
chloric acid,  reduces  the  stannic  to  stannous  chloride  with 
metallic  iron,  and  titrates  with  standard  iodine  solution  (9.7 
gms.  iodine  per  liter  =  about  1  per  cent  Sn  per  cubic  centimeter 
when  0.5  gm.  of  ore  is  used). 

TIN 

GRAVIMETRIC  METHOD 

Mix  1  gm.  of  the  finely  ground  ore  in  a  porcelain  crucible 
with  3  gms.  of  dry  Na2COs  and  3  gms.  of  S.  Cover  the  crucible 
and  heat  gently  over  a  low  flame  until  the  sulphur  has  ceased 
to  escape  and  burn  (about  twenty  minutes).  Cool  the  cru- 
cible and  treat  the  fusion  with  hot  water  in  a  casserole.  The 
tin  should  dissolve  as  sodium  sulpho-stannate. 


Filter  and  wash  the  precipitate  with  hot  water. 

If  the  residue  feels  gritty  under  the  glass  rod,  burn  the  filter,  add 
sodium  carbonate  and  sulphur  and  repeat  the  process  described  above. 
Add  the  filtrate  containing  the  residue  of  tin  to  the  first  filtrate. 

*  "  Technical  Methods  of  Ore  Analysis,"  164a. 
fTreadwell-Hall,  "Analyt.  Chem.,"  1,  222. 


296  METALLURGICAL  ANALYSIS 

Acidify  the  filtrate  with  sulphuric  acid  to  precipitate  the 
tin  as  81182.  Keep  the  solution  warm  while  the  precipitate 
settles.  Decant  the  clear  solution  through  a  filter  and  wash 
by  decantation  with  ammonium  acetate  solution — made  by 
adding  an  excess  of  acetic  acid  to  dilute  ammonia — to  prevent 
the  precipitate  from  running  through  the  filter.  Transfer  the 
precipitate  to  the  filter  and  finally  wash  it  with  hot  water. 
Place  the  filter  and  its  contents  in  a  weighed  porcelain  cru- 
cible. Heat  very  gently  with  free  access  of  air  until  there  is 
no  longer  an  odor  of  burning  sulphur.  Gradually  increase  the 
heat  to  a  high  temperature. 

A  high  temperature  at  first  may  volatilize  SnS2. 

Add  about  half  a  gram  of  ammonium  carbonate  and  heat 
to  drive  out  sulphuric  acid  completely.  Cool,  weigh,  and  repeat 
the  treatment  with  ammonium  carbonate  several  times  until 
the  weight  of  Sn02  is  constant.  The  factor  for  Sn  in  SnC>2 
is  0.78808. 

TIN  IN  CONCENTRATES 

Tin  in  cassiterite  concentrates  may  be  determined  by  the 
fire  assay. 

Mix  5  gms.  of  the  ore  in  a  fire-clay  crucible  with  2  gms.  of 
charcoal,  12  gms.  of  NaHCOs,  and  1  gm.  of  borax  glass.  Cover 
with  salt  and  place  on  top  of  the  charge  several  lumps  of  char- 
coal. Fuse  in  a  muffle  at  a  little  below  white  heat  for  about 
one  hour.  Withdraw  the  crucible  from  the  furnace.  When 
cool  break  the  crucible  and  remove  the  slag  from  the  tin  button 
and  weigh  the  tin. 

TUNGSTEN 

Fuse  1  gm.  of  the  ore  in  a  platinum  crucible  with  4  gms. 
of  sodium  carbonate  for  about  forty  minutes.  Cool  and  extract 
the  fusion  by  boiling  in  water.  Filter. 

The  tungstate  and  silicate  of  sodium  are  soluble. 


VANADIUM  297 

Add  to  the  filtrate  an  excess  of  nitric  acid  and  evaporate 
the  solution  to  dryness.  Add  a  little  hydrochloric  acid,  warm, 
and  dilute  with  hot  water.  Boil  and  filter.  Burn  the  residue 
in  a  platinum  crucible  to  SiO2+WC>3.  Add  hydrofluoric  acid 
and  sulphuric  acid  to  the  crucible  and  evaporate  to  dryness 
to  volatilize  the  silica.  If  necessary,  repeat  the  treatment  to 
volatilize  the  silica  completely. 

Burn  with  the  blast  lamp  and  weigh  as  WOs. 

VANADIUM 

HILLEBRAND'S  METHOD  * 

Fuse  1  to  5  gms.  of  the  ore  with  4  to  20  gms.  of  sodium  car- 
bonate and  0.5  to  3  gms.  of  potassium  nitrate.  Treat  the  fusion 
with  hot  water,  add  a  few  drops  of  alcohol  to  precipitate  man- 
ganese, and  filter. 

If  the  ore  contains  much  vanadium,  some  will  be  retained  by  the 
residue  on  the  filter.  In  this  case,  burn  the  filter  with  the  residue  and 
fuse  it  again  in  the  manner  directed  above. 

Nearly  neutralize  the  filtrate  containing  all  the  vanadium 
with  nitric  acid  to  precipitate  aluminum  hydroxide  and  silicic 
acid. 

Be  careful  not  to  make  the  solution  acid  on  account  of  the  reducing 
action  of  nitrous  acid  formed  from  nitrates  in  the  fusion. 

The  quantity  of  acid  required  to  neutralize  the  sodium  carbonate 
in  the  fusion  can  be  determined  on  a  separate  portion. 

Evaporate  the  solution  nearly  to  dryness.  Treat  with  hot 
water  and  filter.  When  the  filtrate  is  cold,  add  a  nearly  neutral 
solution  of  mercurous  nitrate  to  precipitate  vanadium. 

It  also  precipitates  mercurous  carbonate  and,  if  the  elements  are 
present,  the  chromate,  molybdate,  arsenate,  and  phosphate. 

*  Amer.  Jour.  Science,  6,  209;  Treadwell-Hall,  "Analytical  Chemistry," 
2,  277. 


298  METALLURGICAL  ANALYSIS 

Heat  to  boiling,  filter,  wash  with  a  dilute  solution  of  ammonium 
nitrate.  Dry  and  burn  in  a  platinum  crucible  at  as  low  a  tem- 
perature as  possible.  Add  a  little  sodium  carbonate  and  fuse. 
Cool  and  .treat  with  hot  water. 

If  a  determination  of  chromium  is  desired,  filter  and  determine  it 
colorimetrically,  using  potassium  chromate  for  a  standard. 

Then  acidify  the  solution  slightly  with  sulphuric  acid  and 
precipitate  the  molybdenum,  arsenic,  and  platinum  with  hydro- 
gen sulphide.  Filter,  boil  the  filtrate,  and  pass  a  current  of  CO2 
through  it  to  remove  H2S.  Titrate  the  hot  solution  with  standard 
potassium  permanganate  solution. 

For  the  most  accurate  work,  reduce  the  solution  with  sulphur 
dioxide,  titrate  again,  and  average  the  two  titrations. 

For  reactions  see  page  143. 


URANIUM 

Treat  1  gm.  of  ore  with  strong  nitric  acid  until  there  is  no 
further  action;  add  5  cc.  of  hydrochloric  acid  and  evaporate 
the  solution  to  dryness.  Cool,  add  3  cc.  of  hydrochloric  and  25 
cc.  of  hot  water.  Boil,  filter,  and  wash  with  hot  water.  Dilute 
the  filtrate  to  150  cc.  and  pass  a  current  of  hydrogen  sulphide 
through  the  solution.  Filter,  and  wash  with  hydrogen  sulphide 
water.  Boil  the  filtrate  to  expel  the  hydrogen  sulphide  and  oxi- 
dize by  adding  strong  nitric  acid.  Add  ammonia  until  nearly 
neutral.  Pour  the  solution  into  50  cc.  of  a  20  per  cent  solution 
of  ammonium  carbonate.  Boil,  let  the  precipitate  settle,  filter, 
and  wash.  Acidify  the  filtrate  with  hydrochloric  acid  and  boil 
off  all  the  carbon  dioxide.  Add  an  excess  of  ammonia,  boil  a 
few  minutes,  filter,  wash  with  ammonium  chloride  solution  and 
once  with  water.  Burn  and  weigh  UsOg. 

The  U  may  be  measured  by  titration  as  follows: 

Dissolve   the   precipitate   of   ammonium   uranate   in   dilute 


LITHIUM  299 

sulphuric  acid,  reduce  with  zinc  for  thirty  minutes,  completely 
dissolve  the  zinc,  and  titrate  with  standard  permanganate  solu- 
tion. 

U02S04+H2+H2S04  =  U(S04)2+2H20. 
5U(S04)2+2KMn04+2H20=5U02S04+K2S04+2MnS04+2H2S04. 

The    permanganate   solution   may   be    standardized    against 
iron  and  its  value  in  uranium  calculated. 

238  5 
The  value  of  the  solution  in  iron  multiplied  by  — — : — -  gives 

the  value  in  uranium. 


METHODS    FOR  THE   DETERMINATION  OF  SOME  OF 
THE  RARER  METALS 

LITHIUM 

GOOCH'S  METHOD  * 

Reagent.    Amyl  alcohol.    C5Hi20  (boiling-point  131°  C.). 

Weigh  and  treat  the  sample  according  to  the  Lawrence 
Smith  method  for  alkalies  in  clay,  p.  287,  until  the  alkaline 
chlorides  have  been  weighed.  Evaporate  the  solution  of  the 
alkaline  chlorides,  which  should  not  contain  more  than  0.2  gm. 
lithium  chloride,  to  a  very  small  bulk.  Transfer  the  solution 
to  a  50-cc.  Erlenmeyer  flask,  add  6  cc.  amyl  alcohol,  and  care- 
fully heat  the  mixture  to  boil  off  the  water. 

It  is  advisable  to  fit  the  flask  with  a  two-hole  stopper  provided  with 
intake  and  delivery  tubes  and  draw  a  current  of  dry  air  through  the 
flask  to  assist  in  the  removal  of  water  vapor  and  thereby  prevent 
bumping. 

When  the  water  has  all  been  boiled  out,  the  chlorides  of 
potassium  and  sodium  being  insoluble  in  amyl  alcohol,  are 

*  Proceedings  Amer.  Acad.  of  Arts  and  Sci.,  N.  S.,  14,  177. 


300  METALLURGICAL  ANALYSIS 

precipitated.  Add  2  to  3  drops  of  strong  HC1  to  convert  to 
chloride  the  small  amount  of  LiOH  that  has  been  produced  by 
hydrolysis.  Boil  a  few  minutes  and  filter  while  hot  on  asbestos. 
Wash  with  hot  amyl  alcohol  that  has  been  boiled.  The  filtrate, 
which  contains  the  lithium  and  a  very  small  amount  of  potassium 
and  sodium,  if  they  were  present  in  the  original  material,  is  evap- 
orated to  dryness.  Add  a  little  dilute  sulphuric  acid,  and  filter 
the  solution  from  the  carbonaceous  residue  into  a  weighed  plati- 
num crucible.  Evaporate  the  solution  to  dryness,  ignite  and 
weigh  the  Li2S04.  Deduct  from  this  weight,  if  K  and  Na  were 
present,  0.00041  gm.  for  Na  and  0.00051  for  K  and  0.00092 
gm.  if  both  were  present  for  each  10  cc.  of  amyl  alcohol  in  the 
filtrate.  The  factor  for  Li20  in  Li2S04  is  0.27176. 

STRONTIUM  * 

Reagent.  A  mixture  of  absolute  alcohol  and  ether  in  equal 
parts. 

Strontium  is  precipitated  with  calcium  as  oxalate.  There- 
fore, after  obtaining  the  oxalate  precipitate  according  to  the 
method  for  limestone  (p.  162),  or  for  clay  (p.  286),  burn  the 
oxalates  to  the  oxides  in  a  platinum  crucible  and  weigh.  Then 
dissolve  the  oxides  in  nitric  acid  and  transfer  the  solution  to  a 
20-cc.  flask.  Evaporate  the  solution  to  dryness  and  raise  the 
temperature  to  between  150°  and  160°  C.  Cool  and  add  about 
2  cc.  of  a  mixture  of  equal  parts  of  absolute  alcohol  and  ether 
(as  small  a  quantity  is  used  as  will  dissolve  the  calcium  nitrate). 
Agitate  to  hasten  solution  of  the  calcium  nitrate.  Cork  the 
flask  and  let  it  stand  over  night.  Filter  on  a  very  small  paper 
and  wash  with  the  mixture  of  absolute  alcohol  and  ether.  Let 
the  filter  dry  and  dissolve  the  strontium  nitrate  on  the  filter 
in  a  few  cubic  centimeters  of  hot  water,  letting  the  solution 
run  into  a  small  beaker.  After  washing  the  filter,  precipitate 
*  Hillebrand,  Bull.  422,  U.  S.  Geological  Survey,  p.  119. 


BARIUM  301 

the  strontium  by  adding  to  the  filtrate  a  few  drops  of  sulphuric 
acid.  Add  to  the  solution  an  equal  volume  of  alcohol.  Let 
the  precipitate  settle  twelve  hours,  filter,  burn,  and  weigh  as 
SrS04.  The  factor  for  SrO  in  SrSO4  is  0.5641. 

If  the  material  under  examination  contains  only  a  small  quantity 
of  barium,  it  will  all  pass  into  solution  if  the  precipitation  of  the  oxa- 
lates  of  calcium  and  strontium  is  repeated  in  a  fresh  solution.  If  a 
considerable  quantity  of  barium  is  present,  a  little  will  come  down 
with  the  strontium.  After  weighing  the  strontium  precipitate,  it  should 
be  tested  for  barium. 

BARIUM 

Treat  1  gin.  of  the  material  according  to  the  method  for 
the  analysis  of  clay  (p.  286)  until  the  oxalates  are  filtered  from 
the  solution.  If  the  oxalates  are  dissolved  and  reprecipitated 
in  fresh  solution  once  or  twice,  all  the  barium  will  pass  into 
solution  with  the  magnesium. 

Evaporate  the  solution  to  dryness  and  drive  off  the  ammonium 
salts  by  heat.  Dissolve  the  residue  in  a  little  water,  add  a  little 
hydrochloric  acid  and  a  few  drops  of  sulphuric  acid.  Let  it 
stand  in  a  warm  place  over  night,  filter,  burn,  and  weigh  BaS04. 
The  factor  for  BaO  in  BaSO4  is  0.65699. 


COLUMBIUM  AND  TANTALUM 

Fuse  the  sample  with  acid  potassium  sulphate  until  the  ore 
is  in  solution.  Cool,  add  water,  and  boil  for  some  time.  Colum- 
bic  acid  remains  as  a  precipitate  (impure).  Filter  by  decanta- 
tion  and  digest  with  ammonium  sulphite  to  dissolve  stannic 
and  tungstic  acids.  Wash  with  water  and  treat  the  precipitate 
on  the  filter  with  very  dilute  hydrochloric  acid  to  dissolve  iron 
sulphide. 

Ignite  the  filter  after  adding  ammonium  carbonate  and 
weigh  as  Cb2Os  and 


302  METALLURGICAL  ANALYSIS 


CAESIUM  * 

The  alkalies  are  obtained  as  chlorides.  (See  the  Lawrence 
Smith  Method,  p.  287.)  Add  to  the  cold,  strongly  acid  solu- 
tion of  the  chlorides  a  cold  solution  of  antimonous  chloride 
acidified  with  hydrochloric  acid.  Filter  off  the  white  precipitate 
of  CsC  SbCls  and  wash  with  cold  concentrated  hydrochloric 
acid.  Wash  the  precipitate  into  a  beaker  with  warm  water  and 
warm  to  decompose  it.  Pass  a  current  of  hydrogen  sulphide 
through  the  solution  to  precipitate  antimony  sulphide.  Filter 
off  the  sulphide,  evaporate  the  nitrate  to  dryness  and  weigh 
the  residue  as  CsCl. 

Caesium  chloride  melts  at  a  dull  red  heat  and  is  volatile;  there- 
fore, after  evaporating  to  dryness,  the  temperature  should  not  be 
raised. 

GERMANIUM 

Fuse  the  ore  in  a  porcelain  crucible  with  2  parts  of  sulphur 
and  5  parts  of  sodium  carbonate.  Cool  the  fusion,  treat  it  with 
boiling  water,  and  filter.  Add  to  the  filtrate  an  excess  of 
hydrochloric  acid  to  precipitate  germanium  disulphide.  Filter 
and  wash  with  dilute  hydrochloric  acid  (5  :  100).  Dry  the 
precipitate  and  heat  it  in  a  current  of  hydrogen  or  coal  gas  to 
reduce  it  to  germanous  sulphide.  Dissolve  the  sulphide  in  hot 
hydrochloric  acid  and  pass  through  the  solution  a  current  of 
hydrogen  sulphide.  Filter  and  treat  the  precipitate  with  nitric 
acid  to  convert  the  sulphide  to  insoluble  GeC>2,  which  is  recovered 
in  a  Gooch  crucible  and  weighed. 

*  Cahen  and  Wootton,  "  The  Mineralogy  of  the  Rare  Metals,"  180. 


GLUCINUM  (BERYLLIUM)  303 


GLUCINUM  (BERYLLIUM)  * 

Weigh  1  gm.  of  the  sample  and  treat  it  according  to  the  method 
for  the  analysis  of  clay,  page  286,  to  the  precipitation  of  iron 
and  aluminum  as  hydroxides.  Dissolve  this  precipitate,  which 
also  contains  the  glucinum  hydroxide,  in  as  little  hydrochloric 
acid  as  possible  and  oxidize  by  adding  a  little  nitric  acid.  Nearly 
neutralize  the  solution  with  ammonia  and  evaporate  it  to  25 
cc.  While  hot,  pour  this  solution  into  75  cc.  of  a  20  per  cent 
solution  pure  sodium  bicarbonate,  heated  to  75°  C.  Boil  for 
one-half  minute  after  all  the  carbon  dioxide  has  escaped.  Let 
the  solution  cool  and  the  precipitate  settle.  Filter  off  the 
hydroxides  of  iron  and  aluminum,  which  will  contain  a  little 
glucinum.  Wash  with  a  10  per  cent  solution  of  sodium  bicar- 
bonate heated  to  75°  C.  Dissolve  the  precipitate  in  hydrochloric 
acid,  reprecipitate  as  before,  and  filter  into  the  first  filtrate. 
Acidify  the  filtrate  with  hydrochloric  acid,  boil  off  the  carbon 
dioxide,  add  only  a  slight  excess  of  ammonia  to  precipitate  the 
G1(OH)2,  filter,  and  wash  by  decantation.  Redissolve  the 
precipitate  in  a  little  hydrochloric  acid  and  precipitate  again 
with  ammonia  to  free  it  from  sodium.  Filter  and  wash  the 
precipitate  free  from  chlorides  with  a  2  per  cent  solution  of 
ammonium  nitrate  or  acetate.  Ignite  and  weigh  as  G10. 

THALLIUM 

Treat  1  gm.  of  the  sample  with  10  cc.  of  nitric  acid  and  5 
cc.  of  hydrochloric  acid;  then  add  7  cc.  of  sulphuric  acid  and  boil 
until  the  fumes  of  sulphuric  acid  are  evolved.  Dilute,  filter, 
wash,  pass  a  current  of  hydrogen  sulphide  through  the  filtrate, 
filter,  boil  off  the  excess  of  hydrogen  sulphide,  nearly  neutralize 
with  sodium  carbonate  and  add  an  excess  of  potassium  iodide. 
The  thallium  is  precipitated  as  bright  yellow  TIL  Let  the 

*  Parsons,  "  The  Chemistry  and  Literature  of  Beryllium." 


304  METALLURGICAL  ANALYSIS 

precipitate  settle,  filter  in  a  Gooch  crucible,  wash  with  cold 
water  and  then  with  a  little  alcohol.  Dry  at  100°  C.  and 
weigh. 

CERIUM 

Decompose  the  sample  by  several  partial  evaporations  with 
hydrofluoric  acid.  Filter  off  the  fluorides  and  silicofluorides, 
supporting  the  paper  on  a  platinum  cone;  wash  the  residue 
with  water  acidulated  with  hydrofluoric  acid,  and  then  wash 
it  into  a  platinum  crucible,  add  sulphuric  acid,  and  evaporate 
to  complete  dryness  to  expel  all  the  fluorine.  Burn  the  filter 
paper  and  add  the  ash  to  the  crucible.  Dissolve  the  contents 
of  the  crucible  in  dilute  hydrochloric  acid,  filter,  add  ammonia 
to  the  filtrate  to  precipitate  the  rare  earths  with  possibly  some 
alumina,  filter,  wash  the  precipitate,  dissolve  it  in  hydrochloric 
acid,  and  evaporate  the  resulting  solution  to  dryness.  Add  a 
little  oxalic  acid  solution  and  heat.  Filter  off  the  oxalates  of 
the  rare  earths  and  burn  them  to  oxides.  Dissolve  the  oxides 
in  dilute  sulphuric  acid.  When  cold,  add  an  excess  of  standard 
hydrogen  peroxide  solution  and  titrate  the  excess  of  EbCb  with 
standard  permanganate  solution. 

2Ce(S04).+HaO,=Ce(S04)i+H,SO4+0,. 

If  the  permanganate  solution  has  been  standardized  against 
iron,  the  ratio  of  the  value  in  cerium  to  its  value  in  iron  will  be 
as  140  is  to  56. 

THORIUM  IN  MONAZITE  * 

Heat  gradually  to  a  gentle  fusion  0.5  gm.  of  the  sample 
with  10  gms.  of  potassium  bisulphate  and  0.5  gm.  of  sodium 
fluoride  in  a  platinum  crucible.  Cool  and  dissolve  in  water  and 
a  little  hydrochloric  acid.  Filter  by  decantation,  add  hydro- 

*  Benz,  Zeit.  f.  Angew.  Chein.,  15,  297  (1902). 


YTTRIUM  305 

chloric  acid  to  the  residue,  and  boil.  Dilute  and  filter.  Nearly 
neutralize  the  combined  nitrate  with  ammonia,  being  careful 
not  to  produce  a  precipitate.  Heat  to  boiling,  add  about  4  gms. 
of  ammonium  oxalate  (the  salt)  and  stir  vigorously.  Let  the 
precipitated  oxalates  of  the  rare  earths  stand  twelve  hours, 
filter,  wash  once  with  water  acidulated  with  nitric  acid.  With 
the  wash  bottle  wash  the  precipitate  into  a  porcelain  dish,  using 
strong  hot  nitric  acid  to  dissolve  off  the  last  traces.  Evaporate 
the  solution  to  dryness.  Add  to  the  residue  10"  cc.  of  nitric 
acid  (1.42)  and  20  cc.  of  fuming  nitric  acid,  cover  and  heat 
on  the  water-bath.  When  the  oxalates  are  decomposed,  wash 
off  the  cover  and  wash  down  the  sides  of  the  dish.  Evaporate 
the  solution  to  dryness.  Cool,  add  a  little  water,  boil,  and 
filter.  Dilute  the  filtrate  to  100  cc.  with  a  10  per  cent  solu- 
tion of  ammonium  nitrate.  Heat  to  about  70°  C.,  and  add 
20  cc.  of  a  3  per  cent  solution  of  hydrogen  peroxide.  Filter 
at  once  and  wash  with  hot  water  containing  ammonium  nitrate. 
The  precipitate  may  be  yellow  owing  to  traces  of  cerium  per- 
oxide. 

Ignite  in  a  platinum  crucible  and  weigh  as  ThO2. 

YTTRIUM 

Treat  5  gms.  of  the  sample  in  a  porcelain  dish  with  aqua 
regia  and  evaporate  the  solution  to  dryness.  Cool,  add  water 
and  a  little  hydrochloric  acid  and  boil.  Dilute  the  solution 
and  filter.  Add  ammonium  oxalate  to  the  filtrate  until  a  pre- 
cipitate ceases  to  form.  Filter  off  the  oxalates  of  yttrium  and 
cerium  with  a  little  of  the  oxalates  of  calcium  and  manganese. 
Dry  and  ignite  the  precipitate  and  redissolve  it  in  a  little  hydro- 
chloric acid.  Add  a  saturated  solution  of  potassium  sulphate 
to  precipitate  cerium.  Filter  and  wash  the  precipitate  with 
a  saturated  solution  of  potassium  sulphate.  Add  to  the  filtrate 
a  solution  of  potassium  hydroxide  or  ammonium  oxalate  to 


306  METALLURGICAL  ANALYSIS 

precipitate  the  yttrium.  Filter  and — to  remove  calcium  and 
manganese, "  which  contaminate  the  precipitate — dissolve  in  a 
little  nitric  acid,  evaporate  to  dryness,  and  bake  to  decompose 
the  manganese  salt.  Cool,  add  hot  water,  boil,  and  filter.  Add 
ammonia  to  the  filtrate  to  precipitate  yttrium.  Stir  well  until 
the  calcium  is  dissolved,  filter,  wash,  dry,  burn,  and  weigh  as 
Y203. 

ZIRCONIUM  * 

Fuse  2  gms.  of  the  sample  in  a  platinum  crucible  with  Na2COs. 
Cool  and  digest  the  fusion  with  hot  water,  filter,  and  wash  the 
residue  with  a  dilute  solution  of  Na2COs.  The  zirconium  is 
filtered  off  with  the  residue.  Wash  the  precipitate  into  a  small 
beaker  and  treat  it  with  a  little  more  than  enough  warm  dilute 
sulphuric  acid  to  take  up  all  that  is  soluble.  Do  not  digest  it 
so  long  that  dissolved  silica  gelatinizes. 

Filter  through  the  same  paper  used  for  the  first  filtration 
and  bt  the  filtrate  run  into  a  100  or  150-cc.  Erlenmeyer  flask, 
wash  the  residue,  ignite  it  in  a  platinum  crucible,  add  to  the  res- 
idue hydrofluoric  and  sulphuric  acids,  and  evaporate.  Dilute  the 
solution  and  filter  off  barium,  strontium,  and  calcium  sulphates 
and  add  the  filtrate  to  the  last  filtrate,  which  will  now  contain 
all  the  zirconium  and  rare  earths.  Add  to  the  combined  filtrates 
hydrogen  peroxide  to  oxidize  titanium,  and  a  few  drops  of  a  solu- 
tion of  disodium  phosphate.  Let  the  precipitate  settle  twenty- 
four  to  forty-eight  hours;  all  the  zirconium  is  precipitated  as 
phosphate  with  a  little  titanium. 

If  the  yellow  color  of  the  solution  should  fade  and  disappear, 
add  more  H202. 

Filter  and  treat  the  residue  as  follows  to  free  it  from  titanium: 

Ignite  the  precipitate,  fuse  it  with  Na2COs,  cool  the  fusion 
and  treat  it  with  hot  water,  filter,  ignite  the  precipitate,  and  fuse 
with  potassium  pyrosulphate.  Dissolve  the  fusion  in  hot  water 

*  Hillebrand,  Bull.  422,  U.  S.,  Geological  Survey,  p.  140. 


LUBRICATING  OIL  307 


to  which  has  been  added  a  few  drops  of  dilute  BkSCU.  Pour 
the  solution  into  a  20-cc.  Erlenmeyer  flask,  add  a  few  drops  of 
4  per  cent  H202  solution  and  a  few  drops  of  solution  of  disodium 
phosphate.  Let  the  precipitate  settle  one  to  two  days,  filter, 
ignite  the  precipitate  and  weigh  as  zirconium  phosphate,  50 
per  cent  of  which  is  taken  as  ZrC^,  although  the  theoretical 
factor  is  0.518. 

LUBRICATING  OIL 

Viscosity.  The  viscosity  of  oil  is  determined  by  a  test  with 
the  viscosimeter,  and  is  expressed  by  the  time  required  for  a 
given  quantity  of  oil  at  a  definite  temperature  to  run  through 
an  orifice  of  definite  dimensions.  The  lighter  oils  are  tested  at 
100°  F.  or  lower  and  the  heavier  at  210°  to  212°  F.  Viscosim- 
eters  of  many  designs  can  be  had  of  dealers  in  chemical  supplies. 

Flashing-point  and  Fire  Test.  The  oil  is  very  gradually 
heated  in  a  cup  in  which  is  placed  a  thermometer  so  that  the 
bulb  is  submerged.  At  regular  intervals  a  flame  or  electric 
spark  is  passed  near  the  surface  of  the  oil  and  the  temperature 
noted  when  the  first  flash  is  observed.  The  heating  is  con- 
tinued until  the  oil  burns,  and  the  temperature  is  recorded  as 
the  burning  test,  which  is  usually  60°  to  80°  F.  above  the  flash- 
point. 

Cold  Test.  A  four-ounce  bottle  of  thin  glass  is  filled  one- 
third  full  of  the  oil.  The  bottle  is  closed  with  a  stopper  which 
carries  a  thermometer  so  adjusted  that  the  bulb  is  just  sub- 
merged in  oil.  The  oil  is  now  cooled  down  gradually,  being 
finally  placed  in  a  freezing  mixture  of  ice  and  salt.  The  bottle 
is  frequently  withdrawn  and  examined  to  see  when  the  oil  ceases 
to  flow.  The  temperature  at  which  it  just  ceases  to  flow  is  taken 
as  the  setting  point,  or  cold  test. 

Cold  Test  for  Lighter  Oils.  To  determine  the  setting  point 
of  lighter  oils  (solidifying  above  45°  F.),  it  is  customary  to  cool 


308  METALLURGICAL  ANALYSIS 

the  oil  to  about  20°  F.  below  its  freezing-point  and  then  gradually 
warm  it  until  it  just  begins  to  flow,  at  which  point  the  temperature 
is  taken  as  the  cold  test. 


EXAMINATION   OF   BOILER  WATER 

Total  Solids.  Evaporate  1  liter  of  the  water  to  dryness  in  a 
weighed  platinum  dish  on  a  water-bath. 

If  the  water  is  low  in  total  solids,  2  liters  or  more  should 
be  taken;  if  high  in  total  solids,  half  a  liter  may  be  used.  The 
water  is  added  to  the  dish,  a  little  at  a  time. 

When  dry,  weigh  the  dish  and  contents;  the  weight  of  the 
empty  dish  deducted  leaves  the  weight  of  the  total  solids. 

Mineral  Matter.  Ignite  the  residue  (Total  Solids  above)  in 
the  platinum  dish. 

This  burns  organic  matter,  expels  combined  water  and  C02  from 
calcium  and  magnesium  carbonates. 

Moisten  the  residue  with  a  very  little  water  and  place  it  in 
an  atmosphere  of  CO2  for  an  hour.*  Dry  at  100°  C.,  cool  in  a 
desiccator  and  weigh.  This  gives  the  total  mineral  matter  as 
it  existed  in  the  water. 

Organic  Matter.  Deduct  the  total  mineral  matter  from 
the  total  solids  and  the  difference  represents  the  organic  matter. 

Scale-forming  Constituents.  Treat  the  total  mineral  matter 
with  hot  water  free  from  CO2,  a  little  at  a  time,  filter  and  wash 
with  boiling  water,  using  not  more  than  50  cc.  in  all.  Burn 
the  filter  in  the  platinum  dish  and  weigh.  The  weight  of  the 
residue  represents  the  scale-forming  constituents. 

Non-scale-forming  Constituents.  The  difference  between  the 
total  mineral  matter  and  the  scale-forming  constituents  repre- 
sents the  non-scale-forming  constituents. 

*Stillman,  "Engineering  Chemistry,"  p.  57. 


EXAMINATION    OF  BOILER  WATER  309 


SiC>2,  Fe2O?i  AkOs,  CaO,  and  MgO  in  the   Scale-forming 

Constituents.  Dissolve  the  scale-forming  constituents  in  hydro- 
chloric acid  and  proceed  according  to  the  method  for  limestone 
(p.  160),  for  the  determination  of  insoluble  silicious  matter,  iron 
and  aluminum  oxides,  lime,  and  magnesia. 

SO3  in  the  Scale-forming  Constituents.  Acidify  the  filtrate 
from  the  magnesium  ammonium  phosphate  with  hydrochloric 
acid,  add  barium  chloride  solution,  boil,  let  the  precipitate 
settle,  filter,  burn,  and  weigh  the  BaS04,  from  which  calculate 
the  percentage  of  SO3.  The  factor  for  S03  in  BaSO4  is  0.343. 

Composition  of  the  Scale-forming  Constituents.  The  SO3 
is  combined  with  CaO  to  form  CaSO4.  The  remaining  CaO 
and  the  MgO  are  calculated  to  carbonates.  The  sum  of  the 
CaSO4,  CaCOs,  MgC03,  insoluble  siliceous  matter,  Fe2O3, 
and  A^Os  should  be  equal  to  the  weight  of  scale-forming  con- 
stituents. 

For  a  complete  report  on  the  total  solids,  the  filtrate  from 
the  scale-forming  constituents  should  also  be  analyzed  for  iron, 
lime,  and  magnesia. 

Cl  in  Water.  Add  to  100  cc.  of  the  water  two  or  three  drops 
of  20  per  cent  solution  of  K^CrOi  and  titrate  with  standard  AgN03 
solution  to  the  faint  reddish  color  due  to  silver  chromate. 

NaCl+AgNO,  =  AgCl+NaNO,, 
2AgNO,+K,CrO4  =  Ag2Cr04+2KNO3. 

Run  a  blank  with  100  cc.  of  distilled  water  and  a  few  drops 
of  20  per  cent  solution  of  potassium  dichromate  to  determine 
how  much  AgNO3  solution  is  required  to  produce  the  red  color 
in  the  absence  of  Cl. 

Total  SO3  in  Water.  Add  to  100  cc.  of  the  water  5  cc. 
of  hydrochloric  acid  and  20  cc.  BaCb  solution.  (See  p.  73.) 
Boil  and  let  the  solution  stand  in  a  warm  place  several  hours. 
Filter,  burn,  and  weigh  BaS04,  from  which  calculate  the  per- 
centage of  SO3.  The  factor  for  SO3  in  BaSO4  is  0.343. 


310  METALLURGICAL  ANALYSIS 

NO2  in  Water.  Sprengel's  Color  Method,  modified  by 
Gill.* 

Reagents.  Phenoldisulphonic  acid.  Mix  3  gms.  of  pure  phenol 
(CeHsOH)  with  37  gms.  (20.1  cc.)  of  pure  sulphuric  acid  (1.84) 
in  a  flask  and  heat  six  hours  on  a  water  bath  at  100°  C. 

C6H6OH+2H2S04  =  C6H3OH(SO3H)2+2H20. 

If  the  acid  crystallizes  out  on  cooling,  it  will  be  redissolved  when 
heated. 

Standard  potassium  nitrate  solution.  Dissolve  2.197  gms. 
of  KNOs  in  1  liter  of  water.  One  cubic  centimeter  of  the  solu- 
tion will  contain  1  mgm.  of  N(>2.  To  avoid  errors  of  measuring 
1  cc.  dilute  100  cc.  to  a  liter  and  take  out  10  cc.  for  the  analysis. 
Place  the  10  cc.  in  a  small  evaporating  dish  and  treat  it  exactly 
in  the  manner  described  below  for  the  sample  of  water. 

NC>2.  Take  5  cc.  of  the  water,  add  to  it  enough  pure  silver 
sulphate  to  precipitate  all  the  Cl  from  the  water.  Filter  into 
a  small  porcelain  dish  and  wash.  Evaporate  the  filtrate  on  a 
steam  bath  until  only  a  drop  of  water  remains.  Add  1  cc.  of 
pure  phenoldisulphonic  acid  and  stir;  add  7  cc.  of  distilled  water 
and  stir.  Add  an  excess  of  ammonia  (about  20  cc.  of  sp.gr. 
0.96),  dilute  to  100  cc.  with  distilled  water,  and  compare  the 
solution  in  a  colorimeter  with  a  standard,  similarly  treated, 
or  place  the  solution  in  a  Nessler  tube  and  match  it  with  a 
standard. 


+2(NH4)2S04+6H20. 

Treating  phenoldisulphonic  acid  with  nitric  acid  and  ammonia  pro- 
d,uces  ammonium  picrate,  which  gives  the  solution  a  distinctly  yellow 
color. 

Free  CO2  in  Water.     (Seyler's  method.) 
*  Tech.  Quarterly,  7,  55. 


TEMPORARY  HARDNESS  OF  WATER  311 

Reagents.  N/50  solution  of  sodium  carbonate.  Dissolve 
1.06  gm.  of  freshly  ignited  Na2COs  in  freshly  boiled  water  and 
dilute  to  1  liter  with  cold  water,  free  from  air.  This  solution 
must  be  protected  from  the  air. 

Phenolphthalein  solution.     (See  page  84.) 

Measure  50  cc.  of  the  water  into  a  Nessler  tube. 

Add  25  to  30  drops  of  phenolphthalein  solution  and  titrate 
with  the  standard  sodium  carbonate  solution,  stirring  with  a 
glass  rod  bent  at  the  lower  end  into  a  circle  at  right  angles  to  the 
rod. 

The  end-point  is  more  easily  detected  if  another  Nessler 
tube  containing  water  is  placed  alongside  the  tube  containing 
the  test. 

TEMPORARY  HARDNESS  OF  WATER 

Reagents.  N/10  solution  of  hydrochloric  acid.  Dilute  8  cc.  of 
hydrochloric  acid  to  1  liter,  test  it  against  N/10  sodium  carbonate 
solution,  and  correct  it  if  necessary.  (See  the  method  below.) 

Hydrochloric  acid  of  1.20  sp.gr.  at  15°  C.  contains  469  gms. 
HC1  per  liter. 

Measure  100  cc.  of  the  water,  add  5  drops  of  methyl  orange 
solution  and  titrate  with  N/10  hydrochloric  acid.  At  the  same 
time,  run  a  blank  on  100  cc.  of  distilled  water  and  5  drops  of 
methyl  orange,  titrating  both  to  the  same  color. 


PERMANENT  HARDNESS  OF  WATER 

Reagents.  N/10  alkaline  solution  made  of  equal  parts  of 
sodium,  carbonate  and  sodium  hydroxide  solution,  as  follows: 

Make  a  N/10  solution  of  sodium  hydroxide  (4.0008  gms.  NaOH 
per  liter),  and  a  N/10  solution  of  sodium  carbonate  (5.3  gms. 
per  liter).  Take  25  cc.  of  each  solution  for  the  test. 

Measure  200  cc.  of  the  water  into  a  platinum  or  porcelain 


312  METALLURGICAL   ANALYSIS 

dish,  or  a  Jena  flask  (not  ordinary  glass).  Add  to  it  50  cc. 
of  N/10  alkaline  solution  (mixed  Na2COs  and  NaOH  solutions). 
Boil  until  the  volume  is  reduced  to  a  little  less  than  200  cc. 

CaH2(C03)2+2NaOH=CaC03+Na2C03+2H20 
CaS04+Na2C03  =  CaC03+Na2S04. 

MgH2(C03)2+4NaOH=Mg(OH)2+2Na2C03+2H20. 
MgS04+2NaOH  =Mg(OH)2+Na2S04. 

Dilute  with  water  to  make  the  volume  just  200  cc.  when 
cold.  Let  the  precipitate  of  calcium  carbonate  and  magnesium 
hydroxide  settle.  Filter  or  siphon  off  100  cc.  of  the  clear  solution. 

If  filtered,  discard  the  first  50  cc.  of  the  filtrate,  since  filter  papers 
are  usually  not  neutral. 

Add  5  drops  of  methyl  orange  solution  and  titrate  with 
N/10  hydrochloric  acid,  running  a  blank  at  the  same  time.  The 
difference  between  the  titration  and  25  represents  the  amount 
of  alkali  used  in  the  reactions  above.  Multiply  this  difference 
by  5  to  give  milligrams  per  100,000  in  terms  of  CaCOs.* 

SOFTENING  WATER 

Water  is  usually  softened  by  adding  lime  and  sodium  car- 
bonate. The  lime  precipitates  calcium  from  solution  as  car- 
bonate and  the  magnesium  as  hydroxide. 

CaH2(C03)2+CaO  =2CaCO3+H2O. 
MgH2(C03)2+2CaO  =  2CaC03+Mg(OH) 
MgS04+CaO+H20  =CaS04+Mg(OH)2. 

The  sodium  carbonate  precipitates  calcium  as  carbonate. 

CaS04+Na,CO,  =  CaC03+Na2S04. 
*  Procter,  Jour.  Soc.  Chem.  Jnd.,  23,  8. 


SOFTENING  WATER  313 

To  determine  how  much  of  these  reagents  to  use,  boil  an 
accurately  measured  sample  of  the  water  with  a  measured 
volume  of  standard  solution  of  Ca(OH)2.  Let  it  cool  and  settle; 
then  filter  and  titrate  the  excess  of  Ca(OH)2  with  standard  acid, 
as  described  above  for  permanent  hardness. 

Ca(OH)2+2HCl  =  CaCl2+2H20. 

Then  add  to  the  titrated  solution  a  measured  volume  of 
a  standard  solution  of  sodium  carbonate,  boil,  cool,  settle,  filter, 
and  titrate  the  excess  of  NaoCOs  in  the  filtrate. 

It  must  be  kept  in  mind  that  the  sodium  carbonate  reacts, 
not  only  with  the  sulphates  originally  in  the  water,  but  also  with 
the  CaCb  formed  in  the  previous  titration  for  the  excess  of  lime, 
and  the  necessary  correction  must,  therefore,  be  made.* 

CaCl2+Na2C03  =  CaC03+2NaCl. 
*  Drawe,  Zeit.  Angew.  Chem.,  23,  52. 


314  METALLURGICAL  ANALYSIS 


DETECTION  OF  THE  METALS 

Aluminum  is  precipitated  as  white  gelatinous  hydroxide  by 
ammonia.  When  the  oxide  is  strongly  heated  on  charcoal  with 
cobalt  nitrate  a  bright  blue  mass  is  obtained. 

Antimony.  When  a  small  quantity  of  an  antimony  compound 
is  heated  in  the  upper  reduction  zone  of  a  Bunsen  burner  on  a 
thread  of  asbestos,  the  flame  is  given  a  bluish  tinge  and  when 
a  small  porcelain  basin  rilled  with  cold  water  is  held  above  it,  a 
brownish  black  deposit  of  metallic  antimony  is  deposited  upon 
the  basin,  and  this  is  but  slightly  attacked  by  cold  nitric  acid 
and  is  insoluble  in  sodium  hypochlorite.  Arsenic  gives  a  similar 
reaction,  but  arsenic  gives  a  garlic-like  odor  during  the  reduc- 
tion, and  the  metallic  film  is  readily  soluble  in  the  hypochlorite. 
Antimony  compounds  may  be  obtained  in  solution  by  treating 
with  HC1  or  by  fusing  first  with  potassium  carbonate  and 
potassium  nitrate.  Hydrogen  sulphide  produces  in  acid  solution 
a  very  characteristic  orange-red  colored  precipitate  of  antimony 
trisulphide. 

Arsenic.  Mix  with  sodium  carbonate  and  heat  on  charcoal 
with  the  blowpipe.  All  arsenic  compounds  give  a  garlic  odor. 

Add  to1  concentrated  hydrochloric  acid  a  few  drops  of  an 
arsenite  solution  and  half  a  cubic  centimeter  of  saturated  solution 
of  stannous  chloride  in  hydrochloric  acid,  warm,  and  the  solution 
turns  brown,  then  black. 

Barium.  The  Bunsen  flame  is  colored  a  yellowish-green 
tint  when  any  volatile  barium  compound  is  brought  into  it. 

Soluble  barium  salts  are  distinguished  from  those  of  strontium 
and  calcium  inasmuch  as  they  are  immediately  precipitated  by 
a  solution  of  calcium  sulphate. 

Bismuth.  On  charcoal  with  soda,  bismuth  gives  a  very  char- 
acteristic orange-yellow  sublimate.  Brittle  globules  of  the  metal 
are  also  reduced  on  the  charcoal  when  treated  with  soda. 

Hydrogen  sulphide  precipitates  from  solutions  of  bismuth 


DETECTION  OF  THE  METALS  315 

salts  a  blackish  brown  sulphide  (61283)  insoluble  in  ammonium 
sulphide  and  easily  soluble  in  nitric  acid.  Ammonia  throws 
down  a  white  basic  salt  insoluble  in  excess. 

Cadmium.  Cadmium  is  precipitated  as  a  yellow  sulphide 
by  hydrogen  sulphide.  The  sulphide  is  insoluble  in  ammonium 
sulphide  and  in  the  caustic  alkalies.  On  charcoal  with  soda, 
compounds  of  cadmium  give  a  characteristic  sublimate  of  the 
reddish-brown  oxide. 

To  test  for  cadmium  in  a  sulphide,  roast  it  to  oxide,  and 
reduce  some  of  the  oxide  in  the  upper  reducing  flame  of  the 
Bunsen  burner,  at  the  same  time  holding  a  glazed  porcelain 
dish  which  contains  water  just  above  the  flame  to  receive  a 
brown  coating.  To  the  brown  coating  add  a  drop  of  AgNOs 
solution;  if  Cd  is  present,  black  metallic  silver  will  be  deposited. 

Caesium.  H^PtCle  produces  a  bright  yellow  crystalline  pre- 
cipitate, a  brighter  color  than  the  potassium  salt  thus  produced, 
and  is  much  more  soluble  than  the  potassium  salt.  The  flame 
test  is  reddish  violet,  similar  to  potassium. 

Calcium.  Calcium  compounds  moistened  with  hydrochloric 
acid  and  placed  on  a  platinum  wire  in  the  hottest  part  of  a  Bun- 
sen  flame,  impart  a  red  color  to  the  flame. 

Calcium  may  be  precipitated  from  solution  as  oxalate  by 
first  making  the  solution  ammoniacal  and  then  adding  ammonium 
oxalate  or  oxalic  acid. 

Cerium.  Fuse  with  sodium  carbonate.  Treat  with  dilute 
hydrochloric  acid,  evaporate  to  dryness  and  bake.  Take  up 
with  dilute  hydrochloric  acid,  filter.  Add  ammonia  to  the 
filtrate,  filter.  Dissolve  the  precipitate  in  hydrochloric  acid, 
add  ammonia  and  oxalic  acid,  filter.  Dissolve  the  precipitate  in 
concentrated  hydrochloric  acid,  nearly  neutralize  with  ammonia; 
add  1  cc.  of  hydrogen  peroxide  and  then  ammonia,  drop  by  drop, 
until  just  alkaline.  When  .just  neutral,  white  thorium  peroxide 
is  precipitated;  when  ammoniacal,  the  orange  cerium  peroxide 
is  precipitated. 


316  METALLURGICAL  ANALYSIS 

Chromium.  Chromium  oxide  is  detected  in  its  insoluble 
compounds  by  its  characteristic  green  color.  It  forms  an  emerald- 
green  head  with  borax  or  microcosmic  salt.  Caustic  potash 
or  soda  gives  a  green  precipitate  in  solutions  of  chromic  salts. 
This  dissolves  in  an  excess  of  alkali  in  the  cold,  but  is  precipitated 
on  boiling  the  solution.  The  detection  of  chromic  acid  is  rendered 
easy  by  the  bright  yellow  color  of  its  salts.  The  yellow  color 
of  the  normal  chromates  becomes  red  on  the  addition  of  an 
acid,  and  again  yellow  when  made  alkaline. 

Cobalt.  Ammonium  sulphide  produces  a  black  precipitate 
(CoS)  insoluble  in  acetic  acid  and  in  dilute  hydrochloric  acid. 

Ammonium  sulphocyanate  produces  a  beautiful  blue  color, 
Co(CNS)2. 

With  a  borax  bead  cobalt  gives  the  characteristic  cobalt- 
blue  color. 

Columbium.  Fuse  with  potassium  bisulphate.  Pulverize 
the  fusion  and  treat  it  with  hot  water;  then  treat  it  with  dilute 
hydrochloric  acid.  Digest  the  residue  with  ammonium  sul- 
phide to  remove  W,  Sn,  etc.  Wash  and  treat  again  with  dilute 
hydrochloric  acid.  The  residue  should  be  colorless  and  contain 
only  silica  and  the  oxides  of  columbium  and  tantalum.  This 
residue  in  a  bead  of  microcosmic  salt  is  colorless  if  no  columbium 
is  present  or  if  heated  in  the  oxidizing  flame;  but  if  heated  in 
the  reducing  flame,  columbium  imparts  a  violet  color  to  the  bead, 
or  blue  if  saturated  with  oxide.  Adding  ferrous  sulphate  turns 
the  bead  blood  red. 

If,  when  the  mixed  oxides  are  boiled  in  dilute  sulphuric  acid 
with  metallic  zinc,  the  white  precipitate  turns  intensely  blue, 
and  remains  so  on  dilution,  columbium  is  present;  if  it  turns 
bluish  gray  and  colorless  on  dilution,  tantalum  is  predominant. 

Copper.  Copper  can  easily  be  detected  by  the  reduction 
to  the  red  metallic  bead  on  charcoal  before  the  blowpipe. 

Copper  compounds  moistened  with  HC1  color  the  non- 
luminous  flame  green. 


DETECTION  OF  THE  METALS  317 

An  excess  of  ammonia  added  to  a  nitric  acid  solution  of  copper 
produces  an  azure-blue  color. 

Erbium.  Erbium  oxide  heated  on  a  platinum  wire  colors 
the  flame  distinctly  green. 

Gallium.  If  a  neutral  solution  of  gallium  chloride  be  warmed 
with  zinc,  gallium  oxide  or  basic  salt  separates  but  not  the 
metal. 

Germanium.  Fuse  with  sulphur  and  sodium  carbonate. 
Treat  with  hot  water,  filter,  add  a  few  drops  of  hydrochloric 
acid  to  the  nitrate  to  precipitate  white  germanium  sulphide. 
Filter  and  heat  the  residue  in  a  current  of  hydrogen  to  reduce 
it  to  gray-black  crystalline  germanous  sulphide.  Dissolve  the 
crystals  in  hydrochloric  acid  and  pass  hydrogen  sulphide 
into  the  solution  to  precipitate  reddish-brown  germanous  sul- 
phide. 

Glucinum.  Ammonium  carbonate  produces  a  white  precipi- 
tate, GlCOs,  soluble  in  an  excess  of  the  reagent;  by  boiling 
the  solution  it  is  precipitated  as  a  basic  carbonate. 

Gold.  Gold  may  be  reduced  from  its  ores  on  charcoal  to  a 
yellow  malleable  bead  which  is  soluble  in  aqua  regia;  if  the 
solution  be  dropped  on  filter  paper  and  one  drop  of  stannous 
chloride  added,  a  purple-red  color  is  produced. 

Indium.  Heated  on  charcoal  before  the  blowpipe  it  colors 
the  flame  blue,  and  gives  an  incrustation  of  the  oxide.  It 
slowly  dissolves  in  hydrochloric  and  dilute  sulphuric  acids,  but 
readily  in  nitric  acid. 

Indium.  Ammonium  chloride  produces  in  a  tolerably  con- 
centrated solution  of  iridium  a  dark-red  crystalline  precipitate. 
Indium  is  distinguished  from  platinum  by  the  formation  of  a 
colorless  solution  of  potassium  chloriridiate  when  caustic  potash 
is  added  to  the  chloride  of  the  metal,  and  on  exposure  to  the  air 
this  colorless  solution  first  becomes  red  colored  and  afterward  blue. 

Hydrogen  sulphide  precipitates  brown  iridium  sulphide, 
which  is  soluble  in  ammonium  sulphide, 


318  METALLURGICAL  ANALYSIS 

Iron.  Ferrous  salts  with  potassium  ferricyanide  produce  a 
dark-blue  precipitate. 

Ferric  salts  with  ammonia  or  the  fixed  alkalies  produce  a 
brown  precipitate. 

Ferric  salts  with  potassium  or  ammonium  sulphocyanate  pro- 
duce a  blood-red  colored  precipitate.  Ferrous  salts  with  a  bead 
of  microcosmic  salt  or  borax  is  colored  dark  green.  This  color 
readily  changes  to  yellow  or  reddish  brown  by  oxidation. 

Lead.  With  soda  on  charcoal  a  malleable  globule  of  metallic 
lead  is  obtained  from  lead  compounds;  the  coating  has  a 
yellow  color  near  the  assay.  • 

In  nitric  acid  solution  dilute  sulphuric  acid  gives  a  white 
precipitate  of  lead  sulphate. 

Lithium.  In  the  Bunsen  flame  .a  fine  carmine-red  color  is 
produced,  visible  if  sodium  is  present  by  viewing  the  flame 
through  cobalt  glass. 

Magnesium.  To  a  solution  of  magnesium  add  ammonium 
chloride,  ammonia,  and  sodium  phosphate;  a  white  precipitate 
(MgNJrUPCU)  'forms.  The  action  is  hastened  by  rubbing  the 
sides  of  the  beaker  with  a  glass  rod. 

Manganese.  Ammonium  sulphide  produces  a  flesh-colored 
precipitate. 

A  solution  containing  traces  of  manganese  boiled  in  con- 
centrated nitric  acid  with  lead  peroxide  or  sodium  bismuthate 
and  allowed  to  settle  gives  a  violet-red  colored  solution  (HMnO4). 

The  borax  bead  with  manganese  in  the  oxidizing  flame  gives 
an  amethyst-colored  bead,  and  this  in  the  reducing  flame  becomes 
colorless. 

Mercury.  Stannous  chloride  heated  with  a  solution  of  mer- 
cury precipitates  gray  metallic  Hg. 

Mercury  compounds  mixed  with  sodium  carbonate  and  heated 
in  a  closed  tube  produce  a  gray  mirror  of  metallic  Hg. 

Molybdenum.  To  a  strong  nitric  acid  solution  of  molybde- 
num add  nearly  enough  ammonia  to  neutralize  the  acid  and 


DETECTION  OF  THE  METALS  319 

then  add  a  few  drops  of  sodium  phosphate  solution.  A  bright 
yellow  crystalline  precipitate  forms  when  the  solution  is  warmed. 

A  hydrochloric  or  sulphuric  acid  solution  of  molybdenum, 
to  which  zinc  or  stannous  chloride  is  added,  turns  first  blue, 
then  green,  and  finally  brown. 

Neodymium.  The  didymium  salts  are  violet  and  are  identified 
by  a  characteristic  absorption  spectrum. 

Nickel.  Potassium  cyanide  produces  a  bright  green  precip- 
itate, Ni(CN)2. 

When  nickel  compounds  are  heated  with  reducing  agents 
before  the  blowpipe,  an  infusible  magnetic  powder  is  produced. 
If  this  powder  is  dissolved  in  a  drop  or  two  of  dilute  nitric  acid 
and  evaporated  to  complete  dryness,  a  characteristic  green 
stain  is  obtained  which  becomes  yellow  on  further  heating. 
Nickel  compounds  color  the  borax  bead  brownish  yellow  in  the 
oxidizing  flame,  the  bead  becoming  gray  and  opaque  in  the  reduc- 
ing flame,  owing  to  the  separation  of  the  metallic  nickel.  Nickel 
is  precipitated  in  alkaline  solution  by  ammonium  sulphide, 
which  dissolves  in  an  excess  of  ammonium  sulphide,  forming  a 
dark-colored  solution. 

Osmium.  It  is  dissolved  in  fuming  nitric  acid,  or  by  fusing 
with  sodium  hydroxide  and  potassium  nitrate  and  then  treating 
with  nitric  acid  and  distilling.  Osmic  oxide  (OsCU),  which 
sublimes  at  a  moderately  low  temperature,  passes  over  and  con- 
denses as  a  colorless  crystalline  mass.  The  osmic  pxide  has  an 
odor  similar  to  chlorine  and  is  poisonous. 

Palladium.  Dissolve  in  nitric  acid  or  aqua  regia.  Potassium 
iodide  added  produces  a  black  precipitate,  palladous  iodide 
(Pdl2),  soluble  in  an  excess  of  the  reagent,  but  not  soluble  in 
water,  alcohol,  or  ether.  Mercuric  cyanide,  Hg(CN)2,  produces 
a  yellowish-white  gelatinous  precipitate,  Pd(ON)2,  which,  on 
ignition,  leaves  the  spongy  metal. 

Platinum.  When  heated  with  sodium  carbonate  on  char  coal, 
gray  spongy  metal  is  reduced.  This,  rubbed  on  a  mortar  with 


320  METALLURGICAL  ANALYSIS 

a  pestle,  gives  a  metallic  luster  and  is  insoluble  in  any  single 
acid. 

Potassium.  A  solution  of  H2PtCl6  added  to  concentrated 
solutions  of  potassium  gives  a  yellow  precipitate  K2PtCl6. 
In  the  Bunsen  flame  potassium  gives  a  violet  color,  visible  if 
sodium  also  is  present  if  viewed  through  cobalt  glass. 

Praseodymium.     See  Neodymium. 

Radium.  To  the  Bunsen  flame  a  radium  salt  imparts  an 
intense  carmine-red  color. 

Radium  rays  discharge  a  charged  eletroscope  and  may  be 
used  for  making  photographs  on  ordinary  X-ray  plates. 

Rhodium.  Before  the  blowpipe  on  charcoal  with  sodium 
carbonate  the  salts  of  rhodium  are  reduced  to  the  metal,  which  is 
insoluble  in  aqua  regai,  bat  may  be  dissolved  by  fusing  it  with 
potassium  pyrosulphate  and  then  treating  the  fusion  with  water. 
By  adding  to  this  solution  potassium  hydroxide  and  a  little 
alcohol  the  brown  rhodium  hydroxide  is  formed. 

Rubidium.  A  solution  of  H2PtCle  produces  a  white  crys- 
talline precipitate,  Rb2PtCl6,  which  is  less  soluble  than  the  cor- 
responding potassium  salt  and  more  soluble  than  the  caesium  salt. 

The  flame  test  gives  a  color  similar  to  the  caesium  test. 

Ruthenium.  Ruthenium  is  practically  insoluble  in  all  acids 
and  in  aqua  regia.  Fuse  it  with  potassium  hydroxide  and  potas- 
sium nitrate.  The  resulting  K2RuO4  heated  with  NaCl  in  a 
current  of  chlorine  yields  soluble  K2RuCl6.  The  greenish- 
black  fusion  treated  with  water  yields  an  orange-yellow  solution, 
which  stains  the  skin  black. 

Scandium.  A  hydrochloric  acid  solution  of  scandkim  treated 
with  solid  sodium  silicofluoride  and  boiled  thirty  minutes  gives 
a  precipitate  containing  scandium  free  from  the  rare  earth 
metals. 

Silver.  When  fused  with  sodium  carbonate  on  charcoal  before 
the  blowpipe,  a  bright  metallic  silver  bead  is  produced,  which 
may  be  dissolved  in  nitric  acid  and  precipitated  from  the  solu- 


DETECTION  OF  THE  METALS  321 

tion  by  hydrochloric  acid  as  a  curdy  precipitate  of  silver 
chloride,  or,  if  only  a  trace  of  silver  is  present,  as  a  mere 
opalescence. 

Sodium.  To  a  neutral  or  weakly  alkaline  solution  add  potas- 
sium pyroantimonate,  E^EbSl^Os,  and  a  heavy  white  crystalline 
precipitate,  Na2H2Sb2Os,  is  quickly  formed  by  rubbing  the  sides 
of  the  beaker  with  a  glass  rod. 

Solutions  of  sodium  on  a  platinum  wire  in  a  Bunsen  flame 
give  a  yellow  color. 

Strontium.  Solutions  on  a  platinum  wire  color  the  Bunsen 
flame  carmine  red. 

Strontium  sulphate  is  less  soluble  than  calcuim  sulphate, 
but  more  soluble  than  barium  sulphate. 

Tantalum.     See  Columbium. 

Thallium.  Dissolve  in  dilute  acid,  add  H^S,  filter.  Add 
to  the  filtrate  ammonium  sulphide,  and  filter.  If  thallium  is 
present  in  the  precipitate  it  will  color  the  Bunsen  flame  emerald 
green. 

Thorium.  Fuse  in  a  platinum  crucible  with  sodium  carbo- 
nate. Cool,  dissolve  in  water  and  hydrochloric  acid.  Evaporate 
to  dryness  and  bake.  Take  up  with  dilute  hydrochloric  acid, 
filter.  Add  ammonia  to  the  filtrate,  filter.  Dissolve  the  pre- 
cipitate in  hydrochloric  acid;  reprecipitate  with  oxalic  acid, 
filter,  ignite  the  residue.  Dissolve  in  hydrochloric  acid.  Evap- 
orate to  dryness.  Take  up  with  water.  Add  an  excess  of  sodium 
thiosulphate  and  boil  to  precipitate. 

Tin.  Mercuric  chloride  added  to  a  solution  of  a  stannous 
salt  precipitates  white  mercurous  chloride. 

A  trace  of  stannous  chloride  in  solution  added  to  a  solution 
of  gold  chloride  precipitates  finely  divided  gold,  brown  by 
transmitted  light  and  bluish  green  by  reflected  light. 

Metallic  zinc  precipitates  tin  from  solution  as  a  spongy  mass, 
which  adheres  to  the  zinc. 

Heat  the  ore  on  charcoal  with  sodium  carbonate  or  potassium 


322  METALLUKGICAL  ANALYSIS 

cyanide;  a  metallic  bead  is  produced  which  is  coated  with  white 
oxide  when  the  flame  is  removed. 

Casserite  in  lumps  in  a  test-tube  with  metallic  zinc  and 
dilute  sulphuric  acid  is  soon  coated  with  metallic  tin. 

Titanium.  Titanium  sulphate  with  hydrogen  peroxide  in  a 
slightly  acid  solution  produces  an  orange-red  color,  or  a  clear 
yellow  with  small  amounts  of  titanium.  Vanadic  acid  with 
hydrogen  peroxide  produces  a  similar  effect. 

Tin  or  zinc  in  hydrochloric  acid  solutions  of  titanium  pro- 
duces a  violet  color,  Ti2Cl2. 

Tungsten.  Treat  with  hydrochloric  and  nitric  acids  (4:1) 
and  take  to  dryness,  wash  by  decantation,  add  dilute  hydro- 
chloric acid  and  metallic  zinc,  aluminum,  or  tin  and  shake;  a 
fine  blue  coloration  or  precipitate  is  produced,  W2O5;  the  color 
disappears  when  diluted  with  water. 

Fuse  in  platinum  with  potassium  bisulphate,  digest  with  a 
solution  of  ammonium  carbonate,  filter,  add  to  the  nitrate  a  few 
drops  of  SnCl2  solution,  acidify  with  hydrochloric  acid,  warm 
gently;  a  fine  blue  color  is  produced. 

The  microcosmic  salt  bead  made  in  the  reducing  flame  is 
clear  blue;  if  iron  is  also  present,  the  bead  will  be  red-brown. 
In  the  oxidizing  flame  the  bead  is  colorless. 

Uranium.  Potassium  ferrocyanide  produces  a  brown  pre- 
cipitate, in  dilute  solution  a  brownish-red  coloration. 

The  borax  (or  microcosmic  salt)  bead  is  yellow  in  the  oxidiz- 
ing flame  and  green  in  the  reducing  flame. 

Vanadium.  Vanadium  compounds  can  be  dissolved  by  a 
treatment  with  acids  or  alkalies.  The  hydrochloric  acid  solu- 
tion assumes  a  bright  blue  color  on  addition  of  zinc.  A  solu- 
tion of  hydrovanadic  sulphate  cannot  be  distinguished  in  color 
from  one  of  copper  sulphate  when  sufficiently  diluted  with 
water,  but,  of  course,  does  not  become  colorless  in  the  presence 
of  metallic  iron. 

Solutions  of  certain  vanadates   also   closely  resemble   solu- 


DETECTION  OF  THE  METALS  323 

tions  of  the  chromates.  For  instance,  a  solution  of  the  tetra- 
vanadate  of  potassium,  K^V-iOn,  does  not  differ  in  appearance 
from  one  of  potassium  dichromate.  They  may,  however,  be 
distinguished  from  one  another,  since  the  vanadate  solution  be- 
comes blue  and  the  chromate  assumes  a  green  color  on  deoxida- 
tion.  When  a  solution  of  vanadic  acid  or  an  acid  solution  of  an 
alkali  vanadate  is  shaken  up  with  ether  containing  hydrogen 
peroxide,  the  aqueous  solution  assumes  a  red  color  like  that  of 
ferric  acetate.  This  reaction  serves  to  detect  one  part  of  vanadic 
acid  in  4000  parts  of  the  liquid.  Chromic  acid  does  not  interfere 
with  the  reaction. 

Yttrium.  Extract  the  yttrium  in  the  manner  described 
under  Cerium  and  separate  it  from  the  other  rare  earths  in  a 
solution  of  their  sulphates  by  adding  a  saturated  solution  of 
potassium  sulphate.  Yttrium  sulphate  is  soluble;  the  others 
are  not. 

Zinc.  Ammonium  sulphide  precipitates  ZnS.  Potassium 
ferrocyanide  produces  a  white  precipitate,  Zn2Fe(CN)e.  Before 
the  blowpipe  on  charcoal  with  sodium  carbonate  a  coating  of 
oxide  is  produced  which  is  yellow  while  hot  and  white  when 
cold.  With  cobalt  nitrate  on  charcoal  an  infusible  green  mass 
is  produced. 

Zirconium.  Treat  with  dilute  sulphuric  acid  (2:1),  filter, 
add  ammonia  to  the  cold  filtrate,  filter;  wash,  dissolve  the 
precipitate  in  hydrochloric  acid,  evaporate  to  dryness.  Take 
up  with  a  little  water  and  add  to  the  cold  saturated  solution 
hydrochloric  acid,  drop  by  drop;  if  zirconium  is  present, 
the  oxychloride  will  be  precipitated.  Heat  to  dissolve  the 
precipitate.  Cool  and  after  some  time  fine  silky  needles  of 
ZrOCl2+8H2O  will  precipitate. 


324 


METALLURGICAL  ANALYSIS 


PROPERTIES  OF  THE  ELEMENTS 


Symbol. 

Atomic 
Weight. 

Melting- 
point. 

Boiling-point. 
760  mm. 

Density  at 
Ordinary 
Temp, 
unless 
otherwise 
Stated. 

Aluminum 

Al 

27    1 

658   7 

1800 

2  65 

Antimony  
Argon. 

Sb 
A 

120.2 

39  88 

630 

-188 

1440 

-186 

6.62 

f     liq- 
\   —185° 

Arsenic  

Barium  
Bismuth  

Boron.        .        .... 

As 

Ba 
Bi 

B 

74.96 

137.37 
208.0 

11.0 

850? 

850 
271 

2200-2500 

/   Sublimes 
V            450 

1420 
|  Sublimes 

I    1.4 
}    5.73 

3.75 
9.80 

)    2  5? 

Bromine. 

Br 

79  92 

-7  3 

\      3500? 
63 

/    ' 
/      25° 

Cadmium  
Caesium.             .    .  . 

Cd 
Cs 

112.40 
132  81 

320.9 
26 

778 
670 

\    3.102 
8.64 
1  87 

Calcium. 

Ca 

40  07 

810 

f      29° 

( 

\    1.55 
Diamond 
3.52 

Carbon.  .          ... 

C 

12  00 

>  3600 

< 

Cerium.   . 

Ce 

140  25 

640 

{ 

Graphite 
2.3 
6  68 

Chlorine. 

Cl 

35  46 

—  101  5 

—33  6 

/  liq.  0° 

Chromium  
Cobalt  

Cr 

Co 

52.0 

58.97 

1510 
1490 

2200 

\    2.49 
6.50 
8.6 

Columbium 
(Niobium)  
Copper.    . 

Cb 
Cu 

93.5 
63  57 

2200? 
1083 

2310 

12.75 

8  93 

Dysprosium  

Dy 

162  5 

Erbium  

Er 

167  7 

4  77? 

Europium  

Eu 

152  0 

Fluorine. 

F 

19  0 

—223 

187 

f    Hq. 
J         igy 

Gadolinium. 

Gd 

157  3 

1    1.11? 

PROPERTIES   OF  THE  ELEMENTS 


325 


PROPERTIES  OF  THE  ELEMENTS— Continued 


Symbol. 

Atomic 
Weight. 

Melting- 
point. 

Boiling-point. 
760  mm. 

Density  at 
Ordinary 
Temp, 
unless 
otherwise 
Stated. 

Gallium               .... 

Ga 

69.9 

30 

5.95 

Germanium  
Glucinum 
(Beryllium). 

Ge 
Gl 

72.5 
9.1 

958 
>  1800? 



5.47 
1  93 

Gold  
Helium  

Au 
He 

197.2 
3.99 

1063 
<-271 

2530? 

-268.6 

19.32 

Holmium. 

Ho 

163.5 

Hydrogen  
Indium 

H 
In 

1.008 
114  8 

-259 
155 

-252.7 
1000? 

7  12 

Iodine              .  . 

I 

126  92 

113  5 

184.4 

4  95 

Iridium  

Ir 

193.1 

2300? 

2550? 

22.41 

Iron  
Krypton 

Fe 
Kr 

55.84 
82  92 

1520 
-169 

2450 
—  151  7 

7.86 
liq.  2.16 

Lanthanum. 

La 

139.0 

810? 

6  12 

Lead  

Pb 

207  .  10 

327.4 

1525 

11.37 

Lithium  

Li 

6.94 

186 

>1400 

.534 

Lutecium  
Magnesium  
IVIan^anese 

Lu 
Mg 
Mn 

174.0 
24.32 
54  93 

651 
1225 

1120 
1900 

1.74 

7  39 

Mercury  
Molybdenum  
Neodym  ium 

Hg 
Mo 
Nd 

200.6 
96.0 
144  3 

-38.7 
2500? 
840? 

356.7 
3200? 

13.56 
8.6 
6  96 

Neon 

Ne 

20  2 

-253? 

-239 

Nickel 

Ni 

58.68 

X452 

2330? 

8  9 

Niton  (radium 
emanation) 

Nt 

222  4 

Nitrogen 

N 

14.01 

-210 

—  195  7 

Osmium  

Os 

190.9 

2700? 

22.5 

Oxygen  

O 

16.00 

-218 

-182.9 

Palladium  
Phosphorus 

Pd 
p 

106.7 
31  04 

1549 
44 

2540 

287    ] 

11.4 
Yellow 
1  83 

Platinum 

Pt 

195  2 

1755 

I 
2450? 

Red  2.20 
21  50 

Potassium 

K 

39  10 

62  3 

758 

862 

Praseodymium 

Pr 

140.6 

940? 

6  48 

326 


METALLURGICAL  ANALYSIS 


PROPERTIES  OF  THE  ELEMENTS— Continued 


•   -  .' 

Symbol. 

Atomic 
Weight. 

Melting- 
point. 

Boiling-point. 
760  mm. 

Density  at 
Ordinary 
Temp, 
unless 
otherwise 
Stated. 

Radium  
Rhodium 

Ra 
Rh 

226.4 

102  9 

1940 

2500? 

12  44 

Rubidium  

Rb 

85.45 

38 

696 

1  532 

Ruthenium  
Samarium           .  . 

Ru 

Sa 

101.7 
150.4 

>1950 
1300-1400 

2520? 

12.3 

7  8 

Scandium  

Sc 

44.1 

Selenium  .  .  .  .'  
Silicon      

Se 
Si 

79.2 
28.3 

217-220 
1420 

690 
3500? 

4.8 
2  3 

Silver 

Ae 

107  88 

960  5 

1955 

10  5 

Sodium  

Na 

23.00 

97.5 

877 

971 

Strontium 

Sr 

87  63 

2  54 

Sulphur  

S 

32.07 

f  Si    112.8 
1  Su  119.2 

|       444  .  7 

f    2.07 
{    1  96 

Tantalum    .    .    . 

Ta 

181  5 

[  Sm106.8 
2850 

I    1.92 
16  6 

Tellurium  

Te 

127.5 

452 

1390 

6  25 

Terbium 

Tb 

159  2 

Thallium  

Tl 

204.0 

302 

1280? 

11  9 

Thorium  
Thulium  

Th 
Tm 

232.4 
168.5 

>1700 

11.3 

Tin 

Sn 

119  0 

231  9 

2270 

7  29 

Titanium  
Tungsten  

Ti 
W 

48.1 
184.0 

1900? 
3000 

3700? 

3.54 
17-18  8 

Uranium  
Vanadium  

U 
V 

238.5 
51  0 

1730? 

18.7 
5  5 

Xenon 

Xe 

130  2 

-140 

-109 

Ytterbium 
(Neoytterbium)  .  . 
Yttrium. 

Yb 

Yt 

172.0 
89  0 

3  8? 

Zinc  
Zirconium  

Zn 
Zr 

65.37 
90.6 

419.4 
1700? 

918 

7.1 
4.15 

FACTORS 


327 


TABLE  OF  FACTORS 


Sought. 

Found. 

Factor. 

Log. 

Ae 

AgCl  

0  7526 

87656 

Al 

A12O3  

0  .  5303 

72455 

A12O3  
Ba 

A1P04  
A1PO4  
BaSO4  

0.22187 
0.41873 
0  .  58846 

34,610 
62,193 
76,972 

BaO   

BaSO4  

0.65699 

81,756 

Bi 

BiOCl  

0  8017 

90401 

C 

CO2  

0  .  27273 

43.573 

(BaCO3) 

BaSO4  
BaCO3 

0.05154 
0  06080 

71,214 
78  390 

CaO               .  .      .  . 

CaSO4  

0.4118 

61,469 

CaCO3       

CaO  

1.7847 

25,156 

Cl.  
Fe 

AgCl  
Fe2O3  

0.2474 
0  .  6994 

39,340 

84472 

FeU 

Fe  

1.2865 

10,942 

FeaOs 

Fe. 

1  4298 

15  527 

K2O 

KC1 

0.6317    - 

80051 

KC1               ...... 

K2PtCl6  
K2PtCl6  

0.19376 
0.30674 

28,727 
48,676 

MgO  
Li2O 

Mg2P207  
Li2SO4  

0.3621 
0.27176 

55,879 
43,418 

Na*O  

Ni 

NaCl  
NiO  ' 

0.53028 
0  78576 

72,450 
89529 

p 

Mg2P2O7.     . 

0  27873 

44,518 

P2O5       

Mg2P2O7  

0.6379 

80,475 

Pb  

PbSO4  

0.6831 

83,449 

s 

BaSO4   

0  13738 

13793 

SO3.           

BaSO4  

0.34300 

53,529 

Si 

SiO2 

0  46932 

67  147 

Sn 

SnO2  

0.78808 

89,657 

Sr  

SrSO4  

0.47703 

67,855 

SrO 

SrSO4 

0  5641 

75,136 

Ti 

TiO2 

0.60051 

77,852 

W  

WO3  

0.7931 

89,933 

328 


LOGARITHMS 


0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

123 

456 

789 

10 

0000 

0043 

0086 

0128 

0170 

0212 

0253 

0294 

0334 

0374 

4813 

17  21  25 

2933  38 

11 

12 
13 

0414 
0792 
1139 

0453 
0828 
"73 

0492 
0864 
1206 

0531 
0899 
1239 

0569 

0934 
1271 

0607 
0969 
1303 

0645 

IOO/ 

1335 

0682 
1038 
1367 

0719 
1072 
1399 

0755 
1106 
1430 

48n 

15  19  23 

26  30  34 

3  6  10 

13    6  19 

23  26  29 

14 
15 
16 

1461 
1761 
2041 

1492 
1790 
2068 

1523 
1818 
2095 

1553 
1847 

2122 

1584 
1875 
2148 

1614 

1903 

2175 

1644 
I93T 

2201 

1673 

1959 
2227 

1703 
1987 
2253 

1732 
2014 
2279 

369 
36  8 
35  8 

12     5  18 
ii     4  17 
ii     3  16 

21  24  27 

2O  22  25 
iS  21  24 

17 
18 
19 

230^ 

2553 
2788 

2330 
2577 
2810 

2355 
2601 

2833 

2380 
2625 
2856 

2405 
2648 
2878 

2430 
2672 
2900 

2455 
2695 
2923 

2480 
2718 
2945 

2504 
2742 
2967 

2529 
2765 
2989 

257 
257 
247 

IO      2    15 

9    2  14 
9    i  13 

I/  2O  22 

16  19  21 
16  18  20 

20 

3010 

3032 

3054 

3075 

3096 

3118 

3139 

31603181 

3201 

246 

8     i  13 

15  i?  19 

21 
22 
23 

3222 
3424 
3617 

3243 
3444 
3636 

3263 
3464 
3655 

3284 
3483 
3674 

3304 
3502 
3692 

3324 
3522 
3711 

3345 
3541 
3729 

3365 
356o 

3747 

3385 
3579 
3766 

3404 
3598 
3784 

24  6 
246 
246 

8    10   12 
8    10   12 

7    9  ji 

14  16  8 
14  iS  7 
13  15  7 

24 
25 
26 
^7 
28 
29 

30 

3802 

3979 

4150 

3820 

3997 
4166 

3838 
4014 
4183 

3856 
4031 
42OO 

3874 
4048 
4216 

3892 
4065 
4232 

39°9 
4082 
4249 

3927 
4099 
4265 

3945 
4116 

4281 

3962 
4133 
4298 

245 
235 

235 

7    9  ii 
7    9  10 
7    8  10 

12  14  6 
12  14  5 
"  13  5 

43M 

4472 
4624 

4330 
4487 
039 

4346 
4502 
4654 

4362 
4518 
4669 

4378 
4533 
4683 

4393 
4548 
4698 

4409 
4564 
4713 

4425 
4579 
4728 

4440 

4594 
4742 

4456 
4609 
4757 

2  3  5 
235 
134 

689 
689 
679 

"  13  4 

II  2  4 

10  2  3 

477i 

4786 

4800 

4814 

4829 

4843 

4857 

4871 

4886 

4900 

134 

$79 

10  i  3 

31 

32 
33 

4914 

5051 

5185 

4928 
5065 
5198 

4942 

5079 
5211 

4955 
5092 
5224 

4969 
5105 
5237 

4983 
5H9 

5250 

4997 
5132 
5263 

5011 
5145 
5276 

5024 

5159 
5289 

5038 
5172 
5302 

*  3  4 
134 
134 

678 
5    7    8 
5    6    8 

IO  I  2 

9  i  2 
9  10  12 

34 
35 
36 

5315 
544i 
5563 

5328 
5453 
5575 

5340 
5465 

5587 

5353 
5478 
5599 

5366 

5490 
5611 

5378 
5502 
5623 

5391 

5514 
5635 

5403 
5527 
5647 

54i6 

5539 
5658 

5428 

5551 
5670 

'34 
i  4 

i  4 

5    6    8 
5    6    7 
5    6    7 

9  10  ii 
9  10  ii 
8  10  ii 

37 
38 
39 

5682 
5798 
59" 

5694 
5809 
5922 

5705 
5821 

5933 

5717 
5832 
5944 

5729 
5843 
5955 

5740 
5855 
5966 

5752 
5866 
5977 

5763 

5877 
5988 

5775 
5888 

5999 

5786 

5899 
6010 

*  3 
*  3 
i  3 

5    6    7 
5    6    7 
457 

8  9  10 
8  9  10 
8  9  10 

40 

6021 

6031 

6042 

6053 

6064 

6075 

6085 

6096 

6107 

6117 

1  3 

456 

8  9  10 

41 

42 
43 

6128 
6232 
6335 

6138 
6243 
6345 

6149 
6253 
6355 

6160 
6263 
6365 

6170 
6274 
6375 

6180 
6284 
6385 

6191 
6294 
6395 

6201 
6304 
6405 

6212 
6314 
6415 

6222 

6325 
6425 

i  3 
i  3 
i  3 

4    5    6 
4    5    6 
4    5    6 

7  8  9 
7  8  9 
7  8  Q 

44 
45 
46 
47 
48 
49 

6435 
6532 
6628 

6444 
6542 
5637 

6454 
6551 
6646 

6464 
6561 
6656 

6474 
6571 
6665 

6484 
6580 
6675 

6493 
6590 
6684 

6503 
6599 
6693 

6513 
6609 
6702 

6522 
6618 
6712 

1  3 

*  3 
1  3 

4    5    6 
4    5    6 
4    5    6 

7  8  9 
7  8  9 
7  7  8 

6721 
6812 
6902 

6730 

J82I 

6911 

6739 
6830 
6920 

6749 
6839 
6928 

6758 
6848 
6937 

6767 

6857 
6946 

6776 
6866 
6955 

6785 
6875 
6964 

6794 
6884 
6972 

6803 

6893 
6981 

i  3 
i  3 

i  3 

455 
445 
445 

678 
6  7  8 
6  7  8 

50 

6990 

6998 

7007 

7016 

7024 

7033 

7042 

7050 

7059 

7067 

i  3 

345 

6  7  8 

51 
52 
53 

7076 
7160 
7243 

7084 
7168 
7251 

7093 
7177 
7259 

7101 

7185 
7267 

7110 
7193 
7275 

7118 
7202 
7284 

7126 
7210 
7292 

7135 
7218 
7300 

7143 
7226 
7308 

7152 
7235 
7316 

*  3 

Z  2 
Z  2 

345 

3    4    5 
345 

6  7  8 
6  7  7 
667 

54 

7324 

7332 

7340 

7348 

7356 

7364 

7372 

7380 

7388 

7396 

i  a  a 

345 

667 

LOGARITHMS 


329 


0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

123 

456 

789 

55 

7404 

7412 

7419 

7427 

7435 

7443 

745i 

7459 

7466 

7474 

122 

345 

5  6  7 

56 
57 
58 

7482 
7559 
7634 

7490 
7566 
642 

7497 
7574 
7649 

7505 
7582 
7657 

7513 
7589 
7664 

7520 

7597 
7672 

7528 
7604 
7679 

7536 
7612 
7686 

7543 
7619 

7694 

755i 
7627 
7701 

122 
122 
112 

3  4  5 
345 
344 

567 
5  6  7 
5  6  7 

59 
60 
61 

"62 

63 
64 

7709 

7782 

7853 

7716 
7789 
7860 

7723 
7796 
7868 

773i 
7803 

7875 

7738 
7810 
7882 

7745 
7818 
7889 

7752 
7825 
7896 

7760 
7832 
7903 

7767 

7839 
7910 

7774 
7846 
7917 

112 
112 
112 

344 
344 
344 

5    6 
5    6 
5    6 

7924 
7993 
8062 

7931 
Sooo 
069 

7938 
8007 

8075 

7945 
8014 
8082 

7952 
8021 
8089 

7959 
8028 
8096 

7966 

8035 
8102 

7973 
8041 
8109 

7980 
8048 
8116 

7987 
8055 
8122 

112 
112 
112 

334 
334 
334 

5  6 

5    5 
5    5 

65 

8129 

8136 

8142 

8149 

8156 

8162 

8169 

8176 

8182 

8189 

112 

334 

5  5 

66 
67 
68 
^9 
70 
71 

8i95 
8261 

8325 

202 
267 
S33i 

8209 
8274 
8338 

8215 
8280 
8344 

8222 
8287 
8351 

8228 
8293 
8357 

8235 
8299 
8363 

8241 
8306 
8370 

8248 
8312 
8376 

8254 

8319 
8382 

112 
112 
112 

334 
334 
334 

556 
556 
456 

8388 
8451 
8513 

3395 
8457 
8519 

8401 
8463 

8525 

8407 
8470 
853i 

8414 
8476 
8537 

8420 
8482 
8543 

8426 
8488 
8549 

8432 
8494 

8555 

8439 
8500 
8561 

8445 
8506 

8567 

112 
I    I     2 
I    I    2 

234 
234 
234 

456 
456 
455 

72 
73 
74 

8573 
8633 
8692 

8579 
8639 
8698 

8585 
8645 
8704 

8591 
8651 
8710 

8597 
8657 
8716 

8603 
8663 
8722 

8609 
8669 
8727 

8615 
8675 
8733 

8621 
8681 
8739 

8627 
8686 
8745 

112 
112 

234 
234 

4  5  5 
455 

75 
76 
77 
78 
79 
80 
81 

0751 
8808 
8865 
8921 

»Vb^ 
8814 
8871 
8927 

8762 
8820 
8876 
8932 

8700 
8825 
8882 
8938 

[774 

8831 
8887 
8943 

?779 

8837 
8893 
8949 

070^ 

8842 
8899 
8954 

8791 
8848 
8904 
8960 

8797 

8854 
8910 
8965 

0002 

8859 

8915 
8971 

112 
112 
I    X     2 

233 
233 
233 

455 
445 
4  4  5 

8976 
9031 
9085 

8982 
9036 
9090 

8987 
9042 
9096 

8993 
9047 
9101 

8998 
9053 
9106 

9004 
9058 
9112 

9009 
9063 
9117 

9015 
9069 
9122 

9020 
9074 
9128 

9025 
9079 
9133 

1X2 
112 
112 

233 
233 
233 

445 
445 
445 

82 
83 
84 
~85 
86 
87 
88 
"89 
90 
91 
92 
93 
94 

9138 
9191 
9243 

9*43 
9196 
9248 

9149 
9201 
9253 

9J54 
9206 
9258 

9*599165 
9212  9217 
9263  9269 

9170 
9222 
9274 

9175 
9227 
9279 

9180 
9232 
9284 

9186 
9238 

9289 

112 
I    Z    2 
I    Z     2 

233 
233 
233 

4  4  5 
445 
4  4  5 

9291 

9299 

9304 

9309 

9315 

9320 

9325 

9330 

9335 

9340 

112 

233 

445 

9345 
9395 
9445 

9350 
9400 
9450 

9355 
9405 
9455 

9360 
9410 
9460 

9365 
9415 
9465 

9370 
9420 
9469 

9375 
9425 
9474 

9380 
9430 
9479 

93«5 
9435 
9484 

939° 
9440 
9489 

112 
Oil 
Oil 

233 
223 

223 

445 

344 
344 

9494 
9542 
9590 

9499 
9547 
9595 

9504 
9552 
9600 

9509 
9557 
9605 

9513 
9562 
9609 

9518 
9566 
9614 

9523 
9571 
9619 

9528 
9576 
9624 

9533 
958i 
9628 

9538 
9586 
9633 

Oil 
Oil 
Oil 

223 
223 
223 

344 
344 
344 

9638 
9685 
9731 

9643 
9689 
9736 

9647 
9694 
9741 

9652 
9699 
9745 

9657 
9703 
9750 

9661 
9708 
9754 

9666 
9713 
9759 

9671 
9717 

9763 

9675 
9722 
9768 

9680 
9727 
9773 

Oil 
Oil 
Oil 

2  23 
223 
223 

344 
344 
344 

95 

9777 

9782 

9786 

9791 

9795 

9800 

9805 

9809 

9814 

9818 

Oil 

223 

344 

96 
97 
98 

9823 
9868 
9912 

9827 
9872 
9917 

9832 
9877 
9921 

9836 
9881 
9926 

9841 
9886 
9930 

9845 
9890 

9934 

9850 
9894 
9939^ 

9854 
9899 

9943 

9859 
9903 
9948 

9863 
9908 
9952 

0    T     I 
0   Z     I 
0  Z     I 

223 
223 
233 

344 
344 
344 

99 

9956 

9961 

9965 

9969 

9974 

9978 

9983 

9987 

9991 

9996 

0   Z     I 

223 

3  3  4 

330 


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GAS  FACTORS 


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TEMPERATURE   IN   DEGREES^FAHRENHEIT. 


332 


METALLURGICAL  ANALYSIS 


HYDROCHLORIC  ACID— DENSITY 

Table  showing  the  approximate  quantities  of  hydrochloric 
acid  (sp.gr.  1.20),  and  water  required  to  make  1  liter  of  any 
desired  density  at  15°  C.,  and  also  the  weight  of  HC1  per  liter 
for  each  density. 


Density. 

Cubic  Centimeters  Required  for  1  Liter. 

Grams  HCl  in  1  Liter.* 

HC1  1.20. 

Water,  Approx. 

1.01 

50 

950 

22 

1.02 

100 

900 

42 

1.03 

150 

850 

64 

1.04 

200 

800 

85 

1.05 

250 

750 

107 

1.06 

300 

700 

129 

1.07 

350 

650 

152 

1.08 

400 

600 

174 

1.09 

450 

550 

197 

1.10 

500 

500 

220 

1.11 

550 

450 

243 

1.12 

600 

400 

267 

1.13 

650 

350 

291 

1.14 

700 

300 

315 

1.15 

750 

250 

340 

1.16 

800 

200 

366 

1.17 

850 

150 

392 

1.18 

900 

100 

418 

1.19 

950 

50 

443 

1.20 

1000 

469 

*  Lunge  and  Marchlewski,  1891. 


DENSITY  OF  ACIDS 


333 


SULPHURIC   ACID— DENSITY 

Table  showing  the  approximate  quantities  of  sulphuric 
acid  (sp.gr.  1.84),  and  water  required  to  make  1  liter  of  any 
desired  density  at  15°  C.,  and  also  the  weight  of  EkSCU  per 
liter  for  each  density. 


Density. 

Cubic  Centimeters 
Required  for  1  Liter. 

Grams  * 
H2S04 
in 
1  Liter. 

Density. 

Cubic  Centimeters 
Required  for  1  Liter. 

Grams 
HsSO* 
in 
1  Liter. 

H2S04 
1.84. 

Water. 

H2S04 
1.84. 

Water. 

.02 

18 

987 

31 

1.44 

443 

624 

779 

.04 

35 

976 

62 

1.46 

465 

604 

817 

.06 

53 

960 

93 

1.48 

487 

584 

856 

.08 

71 

949 

125 

.50 

509 

564 

896 

.10 

90 

934 

158 

.52 

532 

540 

936 

.12 

108 

921 

191 

.54 

555 

521 

977 

.14 

126 

908 

223 

.56 

575 

502 

1015 

.16 

146 

891 

257 

.58 

598 

479 

1054 

.18 

166 

874 

292 

.60 

621 

457 

1096 

.20 

186 

858 

328 

.62 

646 

432 

1139 

.22 

207 

839 

364 

.64 

671 

406 

1181 

.24 

227 

822 

400 

.66 

695 

382 

1222 

.26 

247 

805 

435 

.68 

720 

356 

1267 

.28 

268 

786 

472 

.70 

745 

329 

1312 

.30 

290 

767 

510 

.72 

772 

298 

1357 

.32 

312 

746 

548 

1.74 

798 

271 

1404 

.34 

333 

726 

586 

.76 

823 

245 

1451 

1.36 

354 

709 

624 

.78 

854 

208 

1504 

1.38 

376 

688 

662 

.80 

893 

157 

1564 

1.40 

399 

665 

702 

1.82 

932 

105 

1639 

1.42 

421 

645 

740 

1.84 

1000 

1759 

*  Lunge  and  Isler,  1895. 


334 


METALLURGICAL  ANALYSIS 


NITRIC  ACID— DENSITY 

Table  showing  the  quantities  of  nitric  acid  (sp.gr.  1.42),  and 
water  required  to  make  1  liter  of  any  desired  density  at  15°  C., 
and  also  the  weight  of  HNOs  per  liter  for  each  density. 


Density, 
sp.gr. 

Cubic  Centimeters 
Required  for  1  Liter. 

Grams  * 
HNOs 
in 
1  Liter. 

Density, 
sp.gr. 

Cubic  Centimeters 
Required  for  1  Liter. 

Grams 
HNOs 
in 
1  Liter. 

HNOs 
1.42. 

Water. 

HNOs 
1.42. 

Water. 

1.01 

19 

983 

19 

1.22 

434 

605 

430 

1.02 

38 

966 

38 

1.23 

456 

584 

452 

1.03 

57 

949 

57 

1.24 

479 

562 

475 

1.04 

76 

932 

75 

1.25 

503 

538 

499 

1.05 

95 

915 

94 

1.26 

527 

514 

521 

1.06 

114 

898 

113 

1.27 

550 

491 

545 

1.07 

133 

881 

132 

1.28 

573 

468 

568 

1.08 

152 

864 

151 

1.29 

598 

442 

592 

1.09 

171 

847 

170 

1.30 

623 

417 

617 

1.10 

190 

830 

188 

1.31 

649 

389 

643 

1.11 

209 

813 

207 

1.32 

675 

362 

669 

1.12 

229 

795 

227 

1.33 

701 

334 

695 

1.13 

248 

777 

246 

1.34 

732 

302 

725 

1.14 

268 

759 

266 

1.35 

761 

271 

754 

1.15 

288 

741 

286 

1.36 

790 

239 

783 

1.16 

309 

722 

306 

1.37 

822 

203 

814 

1.17 

329 

704 

326 

1.38 

854 

168 

846 

1.18 

350 

684 

347 

1.39 

888 

129 

880 

1.19 

370 

665 

367 

1.40 

922 

90 

914 

1.20 

391 

646 

388 

1.41 

961 

45 

953 

1.21 

412 

626 

409 

1.42 

1000 

991 

Lunge  and  Rey,  1891. 


GENERAL  REFERENCES 

AARON,  C.  H.:   Assaying.     6th  Ed.     San  Francisco.     Mining  and  Scientific 

Press.     1906. 

ALLEN,  J.  A.:  Tables  for  Iron  Analysis.     New  York.     J.  Wiley  &  Sons.     1896. 
Analysis  of  Iron  and  Steel.     Middletown,   Ohio.     American  Rolling  Mill 

Co.     1912. 
ARGALL,  P.  H.:    Smelter  and  Mill  Methods  of  Analysis.     Boulder,  Colo. 

University  of  Colo.     1904. 
BARR,  J.  A.:    Testing  for  Metallurgical  Processes.     San  Francisco.     Mining 

and  Scientific  Press.     1910. 

BERINGER,  C.  AND  J.  J.:  Assaying.     3d  Ed.     London.     Griffin  &  Co.     1895. 
BLAIR,  A.  A.:    The  Chemical  Analysis    of  Iron.     7th  Ed.     Philadelphia. 

Lippincott  &  Co.     1908. 
BLASDALE,  W.   C.:  Principles  of  Quantitative  Analysis.     New   York.     D. 

Van  Nostrand  Co.     1914. 
BREARLEY,  H.,  AND  IBBOTSON,  F.:   The  Analysis  of  Steel  Works  Materials. 

London.     Longmans,  Green  &  Co.     1902. 
BROWNING,  P.  E.:  Introduction  to  the  Rarer  Elements.     3d  Ed.     New  York. 

J.  Wiley  &  Sons.     1914. 
CAIRNS,    F.   A.:    Quantitative    Chemical    Analysis.     3d  Ed.     New  York. 

H.  Holt  &  Co.     1896. 
CARNOT,  A.:    Traite  d'analyse  des  substances  minerales.     Dunod.     Paris. 

1910. 
CHEEVER,    B.    W.:     Select   Methods   in   Inorganic   Quantitative   Analysis. 

Revised  by  F.  C.  SMITH.     3d  Ed.     Ann  Arbor,  Mich.     G.  Wahr.     1896. 
CHESNAU,  M.  G.:  Analytical  Chemistry,  New  York.     Macmillan  &  Co. 
CLASSEN,  A.:  Handbuch  der  analytischen  Chemie.     Stuttgart.     1891. 
CLASSEN,   A.:    Quantitative  Chemical  Analysis  by  Electrolysis.     5th  Ed. 

Trans,  by  W.  T.  HALL.     New  York.     J.  Wiley  &  Sons.     1914. 
CLENNELL,  J.  E.:  Chemistry  of  Cyanide  Solutions.     New  York.     Engineering 

and  Mining  Journal.     1904. 
CROBAUGH,  F.  L.:    Methods  of  Chemical  Analysis  and  Foundry  Chemistry. 

Cleveland,  O.     1901. 
CROOKES,  W.:    Select    Methods  in  Chemical  Analysis.     3d  Ed.     London. 

1894. 

335 


336  METALLURGICAL  ANALYSIS 

CUMMINGS,  A.  C.,  AND  KAY,  S.  A.:   Quantitative  Chemical  Analysis.     New 

York.     J.  Wiley  &  Sons.     1914. 

DENNIS,  L.  M.:  Gas  Analysis.     New  York.     Macmillan  &  Co. 
FRESENIUS,  K.  M.:    Quantitative  Chemical  Analysis.     6th  ed.     Trans,  by 

A.I.  CORN.     New  York      J.  Wiley  &  Sons.     1911. 
FULTON,  C.  H.:   Fire  Assaying.     2d  Ed.     New  York.     McGraw-Hill   Book 

Co.     1911. 
FURMAN,  H.  VAN  F.:   Practical  Assaying.     5th  Ed.     New  York.     J.  Wiley 

&  Sons.     1901. 
GILL,  A.  H.:    Gas  and  Fuel  Analysis  for  Engineers.     3d  Ed.     New  York. 

J.  Wiley  &  Sons.     1903. 
GOOCH,  F.  A.:    Methods  in  Chemical  Analysis.     New  York.     J.  Wiley  & 

Sons.     1912. 
HEESS,  J.  K.:    Practical  Methods  for  the  Iron  and  Steel  Works  Chemist. 

Easton,  Pa.     The  Chemical  Publishing  Co.     1908. 
HEMPEL,  W.:  Gas  Analysis.     New  York.     Macmillan  &  Co. 
HILLEBRAND,  W.  F.:   The  Analysis  of  Silicate  and  Carbonate  Rocks.     Bull. 

422,    U.    S.    Geological    Survey,    Washington,    Government    Printing 

Office.     1910. 
HOWE,  H.  M.:    Metallurgical  Laboratory  Notes.     Boston.     Boston  Testing 

Laboratories.     1902. 
JOHNSON,  C.  M.:    Rapid  Methods  for  the  Chemical  Analysis  of  Special 

Steels.     2d  Ed.     New  York.     J.  Wiley  &  Sons.     1914. 

JULIAN,  F. :  A  Textbook  of  Quantitative  Analysis.     St.  Paul,  Minn.     Ram- 
sey Publishing  Co.     1902. 
KRAYER,  P.  J. :  The  Use  and  Care  of  a  Balance.     Easton,  Pa.     The  Chemical 

Publishing  Co.     1914. 
LODGE,    R.   W.:     Notes    on   Assaying.      New    York.      J.  Wiley    &    Sons. 

1906. 
LORD,  N.  W.,  AND  DEMOREST,  D.  J.:    Metallurgical  Analysis.     New  York. 

McGraw-Hill  Book  Co.     1913. 
Low,  A.  H.:    Technical  Methods  of  Ore  Analysis.     6th  Ed.     New  York. 

J.  Wiley  &  Sons.     1914. 
LUNGE,    G.:     Techno-Chemical   Analysis.     Trans   by   A.    I.    COHN.     New 

York.     J.  Wiley  &  Sons.     1905. 
MAHIN,  E.   G.:    Quantitative  Analysis.     New  York.     McGraw-Hill  Book 

Co.     1914. 
MERCK,  E.:    Chemical  Reagents,  Their  Purity  and  Tests.     2d  Ed.     New 

York.     D.  Van  Nostrand  Co.     1914. 
MENSCHUTKIN,  N.:   Analytical  Chemistry.     Trans,  by  J.  LOCKE.     London. 

Macmillan  &  Co.     1895. 


GENERAL  REFERENCES  337 

MILLER,  E.  H. :   Quantitative  Analysis  for  Mining  Engineers.     2d  ed.     New 

York.     D.  Van  Nostrand  Co.     1907. 
MITCHELL,    J.:     Practical   Assaying.     5th   Ed.     Edited   by   W.    CROOKES. 

London.     Longmans,  Green  &  Co.     1881. 
MORGAN,  J.  J.:    Tables  for  Quantitative  Metallurgical  Analysis.     London. 

Griffin  &  Co.     1899. 
NEUMANN,  B.:  Theorie  und  Praxis  der  analytischen  Elektrolyse  der  Metalle. 

Halle.     W.  Knapp.     1897.     Trans,  by  J.  B.  C.  KERSHAW.     London. 

Whittaker  &  Co. 
OLSEN  J.  C.:    Quantitative  Chemical  Analysis.     4th  Ed.     New  York.     D. 

Van  Nostrand  Co.     1911. 
OSTWALD,  W. :  The  Scientific  Foundations  of  Analytical  Chemistry.     Trans. 

by  G.  McGowAN.     2d  Ed.     London.     Macmillan  &  Co.     1900. 
PHILLIPS,  F.  C.:    Methods  for  the  Analysis  of  Ores,  Pig-iron,  and  Steel. 

2d  Ed.     Easton,  Pa.     The  Chemical  Publishing  Co.     1901. 
PHILLIPS,  H.  J.:   Engineering  Chemistry.     2d  Ed.     London.     C.  Lockwood 

&Son.     1894. 
POST,  J.:  Chemisch-technische  Analyse.     Braunschweig.     F.  Vieweg  &  Sohn. 

1909. 
PRICE,  W.  B.,  AND  MEADE,  R.  K.:   The  Technical  Analysis  of  Brass.     New 

York.     J.  Wiley  &  Sons.     1908. 
PROST,    E.:     Chemical   Analysis.     Trans,     by   J.    C.    SMITH.     New   York. 

D.  Van  Nostrand  Co.     1904. 
RHEAD,  E.  L.,  AND  SEXTON,  A.  H.:    Assaying  and  Metallurgical  Analysis. 

London.     Longmans,  Green  &  Co.     1902. 
RICKETTS,  P.  DE  P.,  AND  MILLER,  E.  H. :    Notes  and  Assaying.     3d  Ed. 

New  York.     J.  Wiley  &  Sons.     1903. 
SEAMON,    W.    H.:     Manual    for    Assayers    and    Chemists.      New    York. 

1910. 
SEXTON,  A.  H. :  The  Chemistry  of  the  Materials  of  Engineering.     Manchester. 

Technical  Publishing  Co.     1900. 
SIDENER,  C.   F.:    Quantitative    Metallurgical  Analysis.     Minneapolis.     H. 

W.  Wilson  Co.     1904. 
SMITH,   E.   A.:     Sampling   and   Assay   of   the   Precious   Metals.     London. 

Griffin  &  Co.     1913. 
SMITH,     E.    F.:     Electro-Analysis.     4th    Ed.     Philadelphia.     P.    Blakiston 

&  Sons      1907. 
STILLMAN,    T.    B.:    Engineering  Chemistry.     4th   Ed.     Easton,    Pa.     The 

Chemical  Publishing  Co.     1910. 
SUTTON,  F.:    A  Systematic  Handbook  of  Volumetric  Analysis.     10th  ed. 

Philadelphia.     P.  Blakiston  &  Sons.     1911. 


338  METALLURGICAL  ANALYSIS 

TALBOT,  H.  P.:    An  Introductory  Course  in  Quantitative  Analysis.     New 

York.     Macmiilan  &  Co.     1899. 
THORPE,  T.  E.:    Quantitative  Analysis.     9th  Ed.     New  York.     J.  Wiley 

&  Sons.     1891. 
TREADWELL,  F.  P.:    Analytical  Chemistry.     Trans,  by  W.  T.  HALL.     3d 

Ed.     New  York.     J.  Wiley  &  Sons.     1914. 
TROILIUS,   M.:    Notes  on  the  Chemistry   of  Iron.     3d  Ed.     New  York. 

J.  Wiley  &  Sons.     1889. 
WASHINGTON,  H.  S.:  The  Chemical  Analysis  of  Rocks.     2d  Ed.     New  York. 

J.  Wiley  &  Sons. 
WHITE,  A.  H.:  Technical  Gas  and  Fuel  Analysis.     New  York.     McGraw-Hill 

Book  Co.     1913. 
WiNKLER,   C.:    Technical   Gas  Analysis.     3d  Ed.     Trans,   by   G.   Lunge. 

London.     Gurney  &  Jackson.     1902. 
WOEHLER,  F.:    Mineral  Analysis.     Edited  by  H.  B.  Mason.     Philadelphia. 

H.  C.  Baird.     1871. 
WYSOR,  H.:   Analysis  of  Metallurgical  and  Engineering  Materials.     Easton, 

Pa.     The  Chemical  Publishing  Co. 


INDEX 


Absorbents  of  hydrochloric  acid,  11G 

of  moisture,  30,  115 
Absorption    bulb    and   tube,    glass- 
stoppered,  124 
Acidity  of  ore,  246 
Adsorption,  27 
Air  bath,  70 
Alkalies  in  clay,  287 
Allen,  nitrogen  in  steel,  151 
Allen  and  Moyer,  Gas  Analysis,  281 
Allihn  condenser,  181 
Alloys,  analysis  of,  210 
Alumina,   determination  of,   in  ore, 

phosphate  method,  87 
in  blast  furnace  slag,  191 
in  iron  slag,  159 
Aluminum,  detection  of,  314 

in  alloy,  213 
Alundum,  reagent,  121 
American     Foundrymen's     Associa- 
tion method  for  sulphur  in  iron, 
110 

Ammonia,  standard  solution  of,  152 
Ammonium  acetate,  solution  of,  175 
bisulphate,  reducing  agent,  131 
carbonate,  reagent,  220 
ferrous  sulphate,  determination  of 

iron  in,  52 

ferrous    sulphate,    standard    solu- 
tion of,  141 

molybdate,   standard  solution  of, 
for  lead,  175 


Ammonium  oxalate  solution,  96 
Ammonium  nitrate,  solution  of,  220 

wash  solution,  76 

phosphate  solution,  97 

phosphate  solution  for  alumina  87 

phosphomolybdate,   reaction   with 
sodium  hydroxide,  85 

phosphomolybdate,  solution  of  in 
ammonia,  79 

sulphate,  wash  solution  of,  81 

sulphocyanate,  solution  of,  220 
Amyl  alcohol,  299 
Analyses,   purposes  for  which  they 

are  made,  1 
Analysis  of  a  gas,  277 

of  iron  ores,  45 

of  iron  slags,  157 

volumetric,  33 
Annealing,  231 
Annealing  cup,  231,  232 
Annealing    steel    for    color    carbon 

determinations,  127 
Anodes,  sampling  of,  198 
Anode  suitable  for  rotating,  174 
Antimony,  detection  of,  314 
Antimony  in  copper,  220 

in  silver  bullion,  202 
Apparatus  for  carbon  in  steel,  com- 
bustion, 117,  122 
for  sulphur  in  iron,  112,  114 
Apparatus,  volumetric,  33 
Argols,  reducing  agent,  227 

339 


340 


INDEX 


Arsenic  and  antimony  in  converter 

copper,  205 

Arsenic,  detection  of,  314 
Arsenic  in  copper,  220 
Arsenic  in  ores,  180 

in  ores  and  furnace  products,  182 

in  ore,  titrating  with  ammonium 
•     thiocyanate,  183 

in  silver  bullion,  202 

in  slag,  195 
Arsenious  acid  method  for  manganese 

in  ore,  90 

Asbestos  felt  for  filtering,  25 
Ash  in  coal,  255 
Aspirator  bottles,  117,  118 
Assay  furnaces,  224 
Assay  of  bullion,  235 

of  gold  and  silver  ores,  224 

of  silicious  gold  and  silver  ore,  229 

of  sulphide  ores,  233 

of  telluride  ores,  234 
Assay-ton,  226 

Atomic  weights  of  the  elements,  324 
Automatic  analysis  of  gas,  282 
Available  cyanogen,  244 

Bailey,  coal  sampling,  253 

Balance,  care  and  use  of,  15 

Ball  mill,  14 

Barium  chloride  solution,  108 

Barium,  detection  of,  314 
determination  of,  301 

Barium  hydroxide   solution   for  car- 
bon dioxide,  125 

sulphate,  contamination  of,  74,  75 
sulphate,  precipitation  of,  109 

Baryta,  194 

Bead  of  gold  and  silver,  225 

Beilstein  and  Jawein,  cadmium,  292 

Bennett,  arsenic,  182 

Benz,  thorium,  304 


Benzoic  acid,  calorific  value  of,  266 

Beryllium,  determination  of,  303 

Berzelius  method  for  silica,  69 

Bismuth,  detection  of,  314 

Bismuth  in  alloys,  218 

Blair,  A.  A.,  fusion  of  ferro-silicon, 

107 

standard  solution  of  iron,  54 
the  reductor,  57 

Blank  test,  58 

Blast  furnace  slags,  chilled,  analysis 

of,  188 
sampling,  188 

"  Blick,"  assaying,  230 

Boat  for  combustion  of  iron  or  steel, 
122 

Boiler  water,  examination  of,  308 
scale-forming  constituents  in,  309 

Bomb  for  calorimeter,  261 

Borax  glass,  melting-point  of,  228 

Boiling-points  of  the  elements,  324 

Brass  and  bronze,  210 

Briquettes    and    other    copper-bear- 
ing products,  analysis  of,  196 

British  thermal  units,  271 

Bronze,  analysis  of,  210 

Brownson,    E.  E.,    copper  analysis, 
206 

Brunck,  O.,  nickel  in  steel,  140 

Brunton,  D.  W.,  sampling,  10 

Bucking  plate,  14 

Buckly,  D.  W.,  bullion  analysis,  199 

Bulb    tube    for    barium    hydroxide 
solution,  125 

Bullion,  assay  of,  235 
gold  in,  240 
sampling  of,  235 
silver  in,  fire  method,  235 

Burettes,  33, 34 

Burning  precipitates,  27 

Burrel,  gas  analysis,  281 


INDEX 


341 


Cadmium  chloride  solution  for  hydro- 
gen sulphide,  1 1 2 
Cadmium,  detection  of,  315 

determination  of,  292 
Cadmium  sulphide,  action  of  hydro- 
chloric acid  on,  114 
Caesium,  detection  of,  315 

determination  of,  302 
Cahen  and  Wootton,  caesium,  302 
Calcium    and   magnesium,    titration 

of,  164 

Calcium  chloride,  action  of  ammo- 
nium oxalate  on,  158 

action  of  oxalic  acid  on,  162 
Calcium,  detection  of,  315 
Calcium     oxalate,     action     of     sul- 
phuric acid  on,  158,  163 
Calculating  results  of  analysis,  31 
Calorie,  definition  of,  260 
Calorific  power  by  the  Parr  calorim- 
eter, 268 

Dickinson's  formula,  267 

formula  for,  266 

of  coal,  260 

of  coal  from  the  ultimate  analysis, 
270 

of  gas,  283 

of  liquid  fuels,  272 
Calorimeter,  260 

water  value  of,  266 
Calorimetry,  corrections  in,  264 
Camera  for  Eggertz  tubes,  43 
Camp,  J.  M.,  gas  factors,  330 

sampling  iron,  103 

sampling  iron-ore,  46,  47 

sulphur  in  iron,  111 

silicon  in  iron  and  steel,  105 

Weller's  method  for  titanium,  135 
Camp's  shaking  machine,  78 
Camphor,  calorific  value  of,  266 
Carbon,  combined,  in  steel,  127 


Carbon,  combustion  apparatus,  117, 

122 

Carbon  filter,  25 
Carbon,  filtering  of,  120 

fixed  in  coal,  256 

hardening,  in  steel,  127 

in  iron  or  steel,  titration  of  excess 
of  barium  hydroxide,  126 

in  steel,  115 

total,     in    iron    or    steel,     direct 
combustion,  121 

weighing  as  barium  carbonate,  124 
Carbon  dioxide,  absorbent  for,  274 

absorption  of,  by  barium  hydrox- 
ide, 125 

apparatus  for,  166 

generator,  64 

in  limestone,  166 

Carbon  monoxide,  explosion  method 
for,  280 

absorbent  for,  276 

calorific  power  of,  285 
Care  and  use  of  the  balance,  15 
Care  of  platinum,  29 
Cargo  sampling,  47 
Cast  iron,  sample,  104 
Cerium,  detection  of,  315 

determination  of,  304 
Chandler,  assay-ton,  226 
Charcoal,  reducing  agent,  227 
Chatard,  tungsten,  148 
Check  assay,  236 
Chlorate  solution,  187 
Chlorine,  absorbents  of,  116 

in  water,  309 
Chromium  and  vanadium  in  steel, 

141 
Chromium,  detection  of,  316 

determination  of,  290 
Classification  of  materials  for  sam- 
pling, 8 


342 


INDEX 


Clay,  analysis  of,  286 

alkalies  in,  287 
Cleaning  solution,  35 
Clennell,  J.  E.,  precipitation  of  zinc 
hydroxide,  246 

total  cyanide,  244 
Coal,  253 

calorific  power  of,  260 

nitrogen  in,  259 

oxygen  in,  260 

phosphorus  in,  260 

proximate  analysis  of,  254 

sampling,  253 

sulphur  in,  256 

ultimate  analysis  of,  259 
Cobalt,  detection  of,  316 

determination  of,  290 
Cochineal,  42 
Coke,  255 

Cold  test  of  lubricating  oil,  307 
Colorimeter,  42,  44 
Colorimetry,  standard  solutions  for, 

43 
Color  method  for  carbon  in  steel,  127 

for  manganese  in  iron  and  steel,  132 

for  manganese  in  ore,  92 
Columbium,  detection  of,  316 
Columbium    and    tantalium,    deter- 
mination of,  301 
Combined  carbon  in  steel,  127 
Combined  water  in  ore,  49 
Commercial    cyanide,    cyanogen    in, 
247 

sampling  of,  247 

Coning  and  quartering  samples,  12 
Constant  temperature  bath,  70 
Converter  copper,  arsenic  and  anti- 
mony in,  205 

copper  in,  205 

Cooke's  apparatus  for  ferrous  iron, 
66 


Cooke's  method  for  ferrous  iron,  65 
Copper  acetate,  action  of  potassium 

iodide  on,  171 
Copper,  analysis  of,  220 
Copper  and  potassium  chloride  solu- 
tion, 115 
Copper  bullion,  analysis  of,  197 

gold  in,  201 

sampling  of,  197 

silver  in,  199,  200 
Copper,  detection  of,  316 
Copper  determinations,  flask  for,  169 
Copper  matte,  analysis  of,  184 
Copper  in  alloy,  211,  214,  217 
Copper  in  blast  furnace  slag,  colori- 
metric  method,  194 

iodide  method,  193 
Copper  in  converter  copper,  205 

in  copper  bullion,  199 

in  matte,  184,  185 

in  ore,  electrolytic  method,  173 

potassium  cyanide  method,  1 68 

potassium  iodide  method,  168 

in  silver  bullion,  202 

in  steel,  150 

volumetric  method,  151 
Copper  in  the  presence  of  arsenic, 
antimony,   tellurium,  and  selen- 
ium, 209 

Copper  oxide  in  the  combustion  fur- 
nace, 123 

Copper  sulphate,  anhydrous,  absorb- 
ent of  hydrochloric  acid,  116 
Correcting  a  standard  solution,  39 
Corrections  in  calorimetry,  264 
Correct  sampling,  necessity  of,  8 
Cover  of  charge  in  assaying,  228 
Counterpoise  in  weighing,  119 
Crucible  assay,  225 
Crucible,  fire  clay,  225 
Crucible  tongs,  230 


INDEX 


343 


Crude    petroleum,    fractional   distil- 
lation of,  272 
Crusher,  13 

Cullen,  J.  F.,  free  metallic  iron,  67 
Cupel,  225 
Cupcllation,  225,  230 

losses  in,  236 
Cupel  tongs,  230 
Cupric  chloride,  action  of,  on  iron, 

120 

Cushman,  oxygen  in  steel,  155 
Cyanide,  action  of  silver  nitrate  on, 

243,  246 

free,  in  solutions,  243 
Cyanide  method  for  copper  in  matte, 

.  185 
Cyanide  solutions,  gold  and  silver  in, 

242 

testing  of,  243 
Cyanogen    in    commercial    cyanide, 

247 
quantity  in  potassium  and  sodium 

cyanides,  244 
reporting  as  potassium  cyanide,  244 

Day  and  Sosman,  melting-point  of 

gold,  243 

melting-point  of  silver,  242 
Decime  salt  solution,  238 
Definition  of  metallurgical  analysis,  1 
Densities  of  the  elements,  324 
Dehydration  of  silicic  acid,  70 
Deposition  of  moisture  while  weigh- 
ing, 31 
Demorest,  D.  J.,  separation  of  zinc 

from  other  metals,  179 
Deniges,  nickel  in  steel,  139 
De  Osa,  nitrogen  in  steel,  153 
Desiccator,  30 

Desulphurizing  agents  for  assaying, 
228 


Deville  and  Stas,  platinum  metals, 

251 
Dewey,  F.  P.,  Gay-Lussac  method 

for  silver,  237 
platinum,  249 
Dickinson's     formula     for     calorific 

power,  267 
Dimethylglyoxime  method  for  nickel 

in  steel,  140 
Direct  combustion  of  iron  or  steel 

for  total  carbon,  121 
apparatus  for,  122 
Dissolving,  18 
Dissolving  a  fusion  from  a  platinum 

crucible,  72 

Distilling  solution  for  arsenic,  180 
Drawe,  water  analysis,  313 
Drown,  T.,  titanium,  98 
Drown's  method  for  silicon  in  iron 

and  steel,  106 
Dulong's  formula,  270 
Duplicate  sampling,  10 

Earnshaw,  calorific  power  of  gas,  285 

Economy  in  the  laboratory,  5 

Eggertz  color  method,  44 
tubes,  43 

Electric  current,  density  of,  for  cop- 
per precipitation,  174 

Electrodes,  platinum,  for  copper,  173 

Electrolytes,  ionization  of,  20 

Electrolytic   method   for   copper   in 

matte,  184 
in  ore,  173 

Elements,  table  of,  324 

Emmerton's  method  for  phosphorus 
in  ore,  80 

Empirical  standard  solutions,  37 

End-point,  41 

Equipment  of  the  laboratory,  5 

Erbium,  detection  of,  317 


344 


INDEX 


Eschka  mixture  for  sulphur  in  coal, 

256 

Ethane,  calorific  power  of,  285 
Ether  method  for  nickel  in  steel,  137 
Ethylene,  calorific  power  of,  285 
Evolution  method  for  sulphur  in  iron 

or  steel,  111 
Explosion  pipette,  274 

Factors,  table  of,  327 
Factor  weights,  32 

for  standard  solutions,  40 
"  Feathers  "  assaying,  230 
Ferric  oxide,  determination  of,  65 
Ferric  salts,  reduction  of,  with  zinc, 

56 
Ferric  sulphate,  standard  solution  of, 

101 

Ferro-manganese  and    spiegel,  man- 
ganese in,  133 

Ferro-silicon,  silicon  in,  107 
Ferrous  iron,  Cooke's  method,  65 

determination  of,  64,  67 
Ferrous  oxide,  determination  of,  65 

in  iron-slag,  159 

in  reverberatory  slag,  195 
Ferrous  salts,  oxidation  of,  by  potas- 
sium permanganate,  57 
Ferrous  sulphate,  reducing  agent,  131 
Ferrous  sulphate,  standard   solution 

for  manganese,  93 
Filtering  by  suction,  23,  24,  25 
Filtration,  35 
Fire  assaying,  224 
Fire  test  of  lubricating  oil,  307 
Fixed  carbon  in  coal,  256 
Flashing-point  of  lubricating  oil,  307 
Flask  for  copper  determinations,  169 
Flour  as  reducing  agent,  177,  227 
Fluids,  sampling  of,  9 
Fluxes,  analysis  of,  253 


Fluxes  for  assaying,  228 

Ford's  method  for  silicon  in  iron,  107 
accuracy  of,  105 

Formula  for  calorific  power,  266 

Fox,  P.  J.,  titration  of  calcium  and 
magnesium,  164 

Fragmental  materials,  sampling  of,  9 

Free  cyanide  in  solutions,  243 

Free  metallic  iron,  determination  of, 
66 

Fuels,  analysis  of,  253 

Furnace,  electric,  for  combustion  of 
carbon,  117 

Fusion,  dissolving  from  a  platinum 
crucible,  72 

Fusions,  contamination  of,  by  sul- 
phur in  gas,  73 

Gallium,  detection  of,  317 
Gas  analysis,  273 

automatic,  282 

record  of,  280 
Gas  burette,  274 
Gas,  calorific  power  of,  283 

from  its  analysis,  285 
Gas  calorimeter,  automatic  recording, 

284 
Gas  combustion  furnace,  method  of 

heating,  119 

Gaseous  mixtures,  gases  in,  275 
Gas  measuring,  277 
Gas  pipettes,  274 
Gay-Lussac    method    for    silver    in 

bullion,  237 
Geissler  bulb,  167 
General  principles  of  sampling,  8 
Germanium,  detection  of,  317 

determination  of,  302 
Glucinum,  detection  of,  317 

determination  of,  303 
Gold  and  silver  bead,  225 


INDEX 


345 


Gold    and   silver   in   copper-bearing 
concentrates,  197 

in  cyanide  solutions,  242 

in  lead  bullion,  241 

in  matte,  188 

in  slag,  196 

Gold  and  silver  ores,  assay  of,  229 
Gold,  detection  of,  317 
Gold  in  bullion,  240 

in  copper  bullion,  201 
Gold-ore,  sampling,  224 
Gold,  pure,  preparation  of,  242 

value  of,  227 
Gooch,  F.  A.,  analysis  of  copper,  220 

lithium,  299 

titanium,  98 
Graduated  cylinder,  19 
Graph  for   correcting   total  rise  in 
temperature  in  calorimetry,  265 
Graphitic  carbon  in  iron,  129 
Gravimetric  analysis,  the  operations 

of,  15 

Gray,  distillation  of  petroleum,  272 
Greenwood,  palladium,  250 

platinum,  250 

Heath,  G.  L.,  sulphur  in  coal,  256 

Hempel,  gas  pipette,  275 

Hillebrand,  W.  F.,  strontium,  300 
titanium,  color  method,  101 
vanadium,  297 
zirconium,  306 

Hofman,  Heine,  and  Hochtlen,  for- 
mation of  Turnbull's  blue,  64 

Holman,  temperature  corrections  in 
calorimetry,  264 

Holmes,  J.  A.,  sampling  coal,  253 

Hood  for  the  laboratory,  4 

Howe,  H.  M.,  segregation,  104 
temperature  correction  in  calorim- 
etry, 264 


Hydrocarbons,  heavy,  absorbent  for, 

276 

Hydrochloric  acid,  absorbents  of,  116 
action  of,  on  permanganate  solu- 
tion, 56 

ammonia  free,  151 
density  table,  332 
normal  solution  of,  36 
standard  solution  of,  126 
Hydrofluoric  acid  method  for  silica, 

69 

Hydrogen,  calorific  power  of,  285 
explosion  method  for,  278,  280 
Hydrogen  in  steel,  153 

apparatus  for,  154 
Hydrogen    peroxide    reaction  •  with 

potassium  permanganate,  96 
standard  solution  for  manganese, 

95 
Hydrogen  sulphide,  action  of  iodine 

on,  114 
generator,  137 
Hydrogen,  weight  of,  69 
Hygroscopic    water,     determination 
of,  49 

Ignition,  loss  on,  50 
Indicator,  35,  41 
Indium,  detection  of,  317 

determination  of,  252 
Inquartation,  232 

Insoluble   silicious   matter   in   lime- 
stone, 160 
Iodide  method  for  copper  in  matte, 

184 

Iodine,  action  of  on  hydrogen  sul- 
phide, 114 
action  of  sodium  thiosulphate  on, 

171 

normal  solution  of,  36 
standard  solution  of,  111,  206 


346 


INDEX 


Iodine,  for  arsenic,  180 
lonization  of  electrolytes,  20 
Iridium,  detection  of,  317 

determination  of,  252 
Iron  and  aluminum  in  alloy,  211 

in  iron-slag,  157 
Iron  and  steel,  analysis  of,  103 

manganese  in,   by  Walters'    color 
method,  132 

phosphorus  in,  129 

sampling,  103 

silicon  in,  105 
Iron,  burning  precipitate  of,  54 

calorific  value  of,  266 

detection  of,  318 

determination    of,    in    ammonium 
ferrous  sulphate,  52 

free  metallic,   in  the  presence  of 
titanium,  68 

graphitic  carbon  in,  129 
Iron  in  alloy,  213 

in  matte,  185 

metallic,  determination  of,  66 
Iron  in  blast  furnace  slags,  190 

in    ore,    potassium    permanganate 
method,  50 

dichromate  method,  62 

in  copper,  220 
Iron-ore,  rare  elements  in,  193 

analysis  of,  45 

sampling,  45 

Iron,    oxidation    of,    by    potassium 
dichromate,  64 

oxidation  of,  with  nitric  acid,  53 

precipitation    of,    with   ammonia, 
53 

reducing  agents  for,  59 

reduction  of  with  sodium  sulphite, 
99 

reduction    of    with    thiosulphate, 
88 


Iron-slags,  analysis  of,  157 
sampling,  157 

Iron,  solution  of,  by  mercuric  chloride 

solution,  67 

sulphur    in,    American    Foundry- 
men's  Association  method,  110 
by  evolution  method,  111 

Johnson,  C.  M.,  chromium  in  steel, 

141 

fusion  of  ferro-silicon,  107 
tungsten,  146 
Jones  reductor,  57 

Julian's   method    for   manganese    in 
ferro-manganese  and  spiegel,  133 
in  ore,  95 
Junkers'  gas  calorimeter,  283 

Keller,  E.,  bullion  assay,  201 

method  for  selenium  and  tellurium 

in  copper,  209 
segregation  in  bullion,  197 
works  laboratory,  7 

Kober  and  Marshall,  indicators,  84 

Laboratory,  economy  in,  5 

equipment  of,  5 

hood  for,  4 

working  table,  3 
Lead  acetate,  solution  of,  148 
Lead  bullion,  gold  and  silver  in,  241 
Lead  button,  225 
Lead,  detection  of,  318 
Lead  in  alloy,  211,  213,  216 

fire  method  for,  177 

in  blast  furnace  slag,  192 

in  copper,  220 

in  matte,  186 

in  ore,  175 

Lead  molybdate  method  for  tungsten 
in  steel,  148 


INDEX 


347 


Lead,  quantity  added,  in  the  bullion 

assay,  237 

reduction  of,  by  carbon,  227 
Lead  sulphate,  action  of  ammonium 

acetate  on,  176 

Leaks  in  combustion  train,  119 
Ledebur's    method    for    oxygen    in 

steel,  155 
Lehner     and     Crawford,     titanium, 

color  method,  136 
Lime  in  blast  furnace  slags,  189 
in  iron-slag,  158 
in  limestone,  gravimetric  method, 

162 

in  ore,  96 

in  reverberatory  slag,  195 
in  slag,  volumetric  method,  158 
volumetric  method,  163 
Limestone,  analysis  of,  160 
carbon  dioxide  in,  166 
lime  in,  162,  163 
magnesia  in,  165 
phosphorus  and  sulphur  in,  166 
sampling,  160 
silica  in,  161 

Liquid  fuels,  calorific  power  of,  272 
Litharge,  melting-point  of,  228 
Lithium,  detection  of,  318 

determination  of,  299 
Logarithmic  table,  328 
Loss  on  ignition,  50 
Low,  A.  H.,  tin,  295,  zinc  by  potas- 
sium ferro-cyanide,  178 
Low-carbon   steel,   solubility  of,   in 

nitric  acid,  105 
Lowe,  fusion  apparatus,  74 
Lubricating  oil,  307 
Lunge's    method    of    standardizing 
potassium    permanganate    solu- 
tion, 55 
Lyon,  D.  A.,  free  metallic  iron,  67 


Magnesia  in  blast  furnace  slag,  190 
in  iron-slag,  159 
in  limestone,  165 
in  ore,  97 

Magnesia  mixture,  79 
Magnesium    ammonium    phosphate, 

burning  of,  80 
Magnesium  chloride,  action  of  sodium 

phosphate  on,  165 
Magnesium,  detection  of,  318 
Magnetic    oxide,     to     prevent    the 
formation    of,    in    burning    iron 
precipitates,  54 
Magnetized  wire  for  transferring  steel 

drillings,  18 

Manganese,  detection  of,  318 
Manganese  dioxide,  action  of  hydro- 
gen peroxide  on,  96 
precipitation  of  with  alcohol,  74 
precipitation    of    with    potassium 

chlorate,  96 
Manganese,  effect  of,  on  color  carbon 

determinations,  128 
Manganese  in  blast  furnace  slag,  191 
in  ferro-manganese  and  spiegel,  133 
in    iron    and    steel,   with    sodium 

arsenite,  132 
in  iron-slag,  160 
in  matte,  187 
in  ore,  color  method,  92 
Julian's  method,  95 
sodium  bismuthate  method,  92 
titration  with  sodium  arsenite,  90 
Volhard's  method,  88 
Walters'  method  for,  132 
Manganese    in    steel,    sodium    bis- 
muthate method,  133 
in  steels  containing  chromium  and 

tungsten,  134 

Manganese  sulphate,  reaction  of  with 
potassium  permanganate,  89 


INDEX 


Manganese  sulphate,  use  of,  in  the 

permanganate  method,  61 
Manganese  sulphide,  action  of  hydro- 
chloric acid  on,  113 

action  of  nitric  acid  on,  108 
Margueritte    method    for    iron    in 

ore,  50 
Marshall,   catalytic  action  of  silver 

nitrate,  91 
Martin,    O.    C.,    analysis    of    silver 

bullion,  202 

Meade,  R.  K.,  analysis  of  alloy,  215 
Measuring  flasks,  33,  34 
Measuring  solvents,  19 
Melting-points  of  the  elements,  324 
Meniscus,  to  render,  visible,  35 
Menschutkin,  platinum  metals,  251 
Mercaptans,  113 

Mercuric  chloride,  reduction  of,  to 
mercury  by  stannous  chloride, 
61 

solution  of,  59 
Mercury,  detection  of,  318 

determination  of,  293 
Metallic  iron,  determination  of,  66 
"  Metallics  "  in  ore,  224 
Metals  as  reagents  in  assaying,  229 
Metals,  detection  of,  314 

reduction  of,  in  contact  with  plati- 
num, 27 

sampling  of,  9 

Metallurgical  analysis,  definition  of,  1 
Methane,  277 

calorific  power  of,  285 

explosion  method  for,  278,  280 
Methods  of  analysis,  selection  of,  1 
Methyl  orange,  42 
Metric  ton,  227 
Mill  solutions,  protective  alkali  in, 

245 
Minor  metals,  determination  of,  290 


Mixer  and  Dubois,  reduction  of  iron 

with  stannous  chloride,  60 
Moisture,  absorbents  of,  30,  115 
deposition  of  while  weighing,  31 
in  coal,  254 
in  ore,  48 

Moisture  sample  of  iron-ore,  47 
Mold,  cast-iron,  for  fusions,  226 

for  sample  of  cast  iron,  104 
Molybdate  method  for  lead  in  ore, 

175 

Molybdate  solution,  76 
Molybdenum,  detection  of,  319 

in  steel,  148,  149 
Molybdenum  powders,  molybdenum 

in,  149 
Molybdic  acid,  reduction  of,  in  the 

reductor,  82 
with  powdered  iron,  83 
Moore,  nickel  in  steel,  139 
Muffle  furnaces,  224 
Muller,  14 
Mylius  and  Forster,  rhodium,  252 

Nails,  iron,  in  assaying,  233 
Necessity  of  correct  sampling,  8 
Neodymium,  detection  of,  319 
Nessler  reagent,  152 
Nickel  and  cobalt,  determination  of, 

290 
Nickel  chloride,  action  of  dimethyl- 

glyoxime  on,  141 
action   of  potassium   cyanide  on, 

139 

Nickel,  detection  of,  319 
Nickel  in  copper,  220 

in  steel,  dimethylglyoxime  method, 

140 

ether  method,  137 
potassium  cyanide  method,  139 
Nickel,  standard  solution  of,  139 


INDEX 


349 


Nitric  acid  density  table,  334 
Nitric    acid,    standard    solution   of, 

245 
standard  solution  for  phosphorus, 

84 
Nitrogen  in  coal,  259 

in  steel,  151 
Normal  solution  of  hydrochloric  acid, 

36 

of  iodine,  36 

of  potassium  dichromate,  36 
of  potassium  permanganate,  36 
of  sulphuric  acid,  36 
Normal  solutions,  36 

Occlusion  of  solutes  in  precipitates, 

27 

Oil,  water  in,  273 

Olsen,  J.  C.,  standardization  of  per- 
manganate solutions,  55 
Operations  of  analysis,  15 
Ore,  acidity  of,  246 
Orsat  apparatus,  281 
Osmium,  detection  of,  319 
Ostwald,  W.,  adsorption,  27 

indicators,  84 

precipitation,  20 
Oven,  Freas  electric,  70 
Oxalic  acid,  action  of  potassium  per- 
manganate on,  158 

solution  of,  160 

standard  solution  of,  245 
Oxides  of  iron,  aluminum,  etc.,  161 
Oxidizing  agents  for  assaying,  227 

for  carbon  monoxide,  116 
Oxygen,  absorbents  for,  276 
Oxygen  for  combustion,  122 

apparatus  for,  155 

in  coal,  260 

Oxygen,  use  of  in  burning  precipi- 
tates, 28 


Palladium,  detection  of,  319 

determination  of,  250 
Palladium  nitrate,  action  of  mercuric 

cyanide  on,  251 

Palladium  oxide,  formation  of,  251 
Palladium,  reduction  of  with  formic 

acid,  251 

Parr,  bomb  for  calorimeter,  261 
calorimeter,  269 
sulphur  in  coal,  257,  258 
Parsons,  beryllium,  303 
Parting  in  assaying,  230 
Pemberton's  alkalimetric  method  for 

phosphorus  in  ore,  83 
Penfield,  S.  L.,  method  for  combined 

water,  49 

Penny's  method  for  iron,  62 
Permanganic  acid,  formation  of  with 

ammonium  persulphate,  91 
Peters,  E.  D.,  sampling,  10 
Petroleum,  271 

sulphur  in,  272 
Phillips,  mercaptans,  113 
Phenoldisulphonic  acid,  reagent,  310 
Phenolphthalein,  41 

solution  of,  84,  126,  245 
Phosphate   method   for   alumina   in 

ore,  87 

Phosphate  precipitate,  care  in  burn- 
ing, 98 

Phosphorus    and    sulphur    in    lime- 
stone, 166 
Phosphorus,  determination  of,  in  ore 

in  the  presence  of  titanium,  86 
Phosphorus   from   the  filtrate  from 

silica,  78 
in  alloy,  214 
in  coal,  260 
in  iron  and  steel,  129 
in  ore,  Emmerton's  method,  80 
rapid  method,  131 


350 


INDEX 


Pemberton's  alkalimetric  method,  83 
weighing     as    magnesium     pyro- 

phosphate,  79,  82 
weighing  the  yellow  precipitate,  75 
Phosphorus,    precipitation    of,    with 

ammonium  molybdate,  77 
temperature  for  precipitating,  78 
Pick  for  sampling,  45 
Pig-copper,  moisture  in,  198 
Pincette,  use  of,  18 
Pipette,  automatic  filling,  127 

how  to  fill,  34 
Pipettes,  33,  34 

Plan  of  a  school  laboratory  for  metal- 
lurgical chemistry,  2 
of  a  works  laboratory,  6 
Platinized  asbestos  in  the  combustion 

furnace,  123 
Platinum,  249,  250 

action  of  phosphorus  on,  166 
care  of,  29 
detection  of,  320 
how  to  clean,  29 
Platinum  metals,  249,  251 
Platinum  in  iron  solution,  effect  with 

stannous  chloride,  60,  63 
Platinum,  reagents  which  attack,  29 
Point  of  rest  of  the  balance,  16 
Potash-bulb,  117,  124 
stoppers  for,  118,  121 
weighing,  119,  121 
Potassium  carbonate,  melting-point 

of,  228 
Potassium  cyanide  method  for  nickel 

in  steel,  139 

standard  solution  for  nickel,  139 
standard  solution  of,  for  copper, 

168 

Potassium,  detection  of,  320 
Potassium    dichromate    method    for 
iron,  62 


Potassium  dichromate,  normal  solu- 
tion of,  36 

standard  solution  of,  62 
Potassium    ferricyanide    solution    as 

indicator,  62 
Potassium  ferrocyanide,  solution  of, 

246 

standard  solution  of,  for  zinc,  178 
Potassium     hydroxide    solution    for 

carbon  dioxide,  115,  123 
Potassium  iodide,  action  of  silver  on, 

243 
Potassium  iodide  method  for  copper 

in  ore,  171 
solution  of,  243 
Potassium  nitrate,  standard  solution 

of,  310 
Potassium  permanganate  method  for 

iron  in  ore,  50 
reduction  with  stannous  chloride, 

59 
Potassium     permanganate,     normal 

solution  of,  36 

reaction  of  with  ferrous  iron,  57 
reaction  with  manganese  sulphate, 

89 

Potassium    permanganate     solution, 
how  to  make  and  standardize,  51 
Lunge's    method    of    standardiza- 
tion, 55 
standardization  of,  for  phosphorus, 

81 

standardization  with  iron  wire,  54 
standardization  with  oxalic  acid,  55 
Praseodymium,  detection  of,  320 
Precautions  in  weighing,  18 
Precious  metals,  assaying,  224 
Precipitates,  burning  of,  27 
occlusion  of  solutes  in,  27 
solubility  of,  20 
washing  of,  26 


INDEX 


351 


Precipitates,  weighing  of,  30 
Precipitate,  transferring  to  a  crucible, 
27 

transfer  of,   from  filter  paper  to 

beaker,  61 
Precipitation,  20 
Preliminary  assay,  236 
Preparation  of  pure  gold,  242 

of  pure  silver,  242 

of  sample  of  iron-ore,  48 
Preuss,  fusion  of  ferro-silicon,  107 
Price  and  Meade,  copper  by  electrol- 
ysis, 173 

distillation  of  arsenic,  181 

nickel,  290 

Proctor,  hardness  of  water,  312 
Protective  alkali  in  mill  solutions,  245 

in  the  presence  of  zinc,  246 
Proximate  analysis  of  coal,  254 
Prussian  blue,  64 
Pulverizer,  14 

Pure  silver,  preparation  of,  242 
Pure  gold,  preparation  of,  242 
Purity  of  reagents,  19 

in  assaying,  229 

Purposes    for    which    analyses    are 
made,  1 

Radium,  detection  of,  320 

Rapid  burning  of  precipitates  with 

oxygen,  28 
Rapid    method    for    phosphorus    in 

iron  and  steel,  131 
Rare  elements  in  iron  ore,  103 
Rarer  metals,  determination  of,  299 
Reading  the  burette,  35 
Reagents,  19 

purity  of,  in  assaying,  229 
Recording  and  checking  a  weight,  18 
Red  lead  oxide,  reagent,  123 
Reducing  agents  for  assaying,  227 


Reducing  agents  for  iron,  59 

Reducing  power,  227 

Reduction  of  ferric  salts  with  zinc, 

56 
Reduction  of  metals  in  contact  with 

platinum,  27 
Reductor,  Jones,  57 

use  of,  58 

Reed,  S.  A.,  sampling,  10 
References,  general,  335 
Reinhardt,  G.  A.,  free  metallic  iron, 

67 

Reverberatory  slag,  analysis  of,  195 
Rhodium,  detection  of,  320 

determination  of,  252 
Richards,  R.  H.,  sampling  table,  11 
Richards,   T.  W.  and   Jesse,    R.  H. 

•calorific  power,  272 
Richards,  T.  W.  and  Shipley,  static 
electric  charges  in  weighing,  119 
Richards,  T.  W.,  gas  pipette,  275 

occlusion,  27 
Rickard,  T.  A.,  sampling  ore  in  place, 

8 

Riffle  for  dividing  sample,  13 
Rope-net  system  of  sampling  ore,  47 
Rose,  T.  K.,  losses  of  gold  in  cupel- 

lation,  240 

Rubidium,  detection  of,  320 
Ruthenium,  detection  of,  320 

determination  of,  252 

Sample  for  moisture,  47 
Sample  grinder,  mechanical,  14 
Sample  of  iron-ore,  preparation  of,  48 
Sample,  quantity  to  be  taken,  10 
Sampler,  Vezin,  12 
Sampling,  8 

Sampling  a  cargo  of  iron-ore,  47 
Sampling,  A.  Van  Zwaluwenburg,  10 
Sampling  blast  furnace  slags,  188 


352 


INDEX 


Sampling,  classification  of  materials  | 


for,  8 

coning  and  quartering,  12 
done  by  chemist,  8 

D.  W.  Brunton,  10 

E.  D.  Peters,  10 
Sampling  fluids,  9 

fragmental  materials,  9 

gas,  273 

general  principles  of,  8 
Sampling  in  duplicate,  10 

iron  and  steel,  103 

iron-ore,  45 

limestone,  160 

metals,  9 
Sampling,  object  of,  8 

of  bullion,  235 

of  copper  bullion,  197 

ore  in  cars,  45 

ore  in  place,  8 

petroleum,  271 

pick,  45 

riffle,  13 

rope-net  system,  47 

S.  A.  Reed,  10 

split  shovel,  12 
Sampling  table,  R.  H.  Richards,  11 

trowel,  45 

Sand-soap  for  cleaning  platinum,  29 
Sauveur,  A.,  forms  of  carbon  in  steel, 
115 

segregation,  104 
Scandium,  detection  of,  320 
Scorification  assay,  225 

of  silver  ores,  234 
Scorifier,  225,  226 
Scorifier  tongs,  235 
Sea-sand  for  cleaning  platinum,  29 
Segregation  of  impurities  in  iron  and 
steel,  104 

of  sulphur  in  iron,  104 


Selection  of  methods  of  analysis,  1 
Selenium   and  tellurium   in   copper, 

209 

Separatory  funnel,  137 
Seyler,  carbon  dioxide  in  water,  310 
Shaking  machine,  Camp's,  78 
Silica,  action  of  as  a  flux,  228 

fusion  with  sodium  carbonate,  71 

hydrofluoric  acid  method,  69 

in  blast  furnace  slags,  188 

in  iron-slag,  157 

in  limestone,  161 

in  ore,  Berzelius  method,  69 

in  reverberatory  slag,  195 

melting-point  of,  228 

purification  of    with    hydrofluoric 

acid,  71,  105 
Silicates,  solution  of  in  hydrochloric 

acid,  70,  72 
Silicious  fluxes.  253 
Silicic  acid,  dehydration  of,  70 
Silicide  of  iron,  action  of  nitric  acid 

on,  105 
Silicon  in  ferro-silicon,  107 

Drown's  method,  106 

Ford's  method,  107 

in  iron  and  steel,  105 

in  steel,  Drown's  method,  106 
Silicon  mixture,  Drown's,  106 
Silicon  tetrafluoride,  formation  of,  71 
Silver  and  gold  in  copper  bullion,  201 
Silver  bullion,  copper,  arsenic,  and 

antimony  in,  202 
Silver,  detection  of,  320 

Guy-Lussac  method,  237 

in  bullion,  fire  method,  235 

in  copper  bullion,  199 

in    ores,    scorification    method    of 

assay,  234 

Silver  foil,  absorbent  of  chlorine,  116 
Silver  nitrate  as  catalyzer,  91 


INDEX 


353 


Silver  nitrate,  standard  solution  of, 
243 

Silver,  standard  solution  of,  237 

Silver  sulphate,  absorbent  of  hydro- 
chloric acid,  116 

Simmance-Abady  automatic  gas  ana- 
lyzer, 282 

Size  of  sample,  10 

Skinner  and   Hawley's  method   for 
arsenic,  180 

Slawik,  vanadium,  color  method,  145 

Slime,  weight  of  ore  in,  248 

Smith,  E.  F.,  copper  by  electrolysis, 
173 

Smith,  J.  Lawrence,  alkalies  in  clay, 
287 

Smoot,  loss  of  platinum,  250 

Soda-lime,  116 

Sodium  arsenite,  standard  solution, 
90 

Sodium  bismuthate  method  for  mag- 
ganese  in  ore,  92 

Sodium  carbonate,  melting-point  of, 

228 
normal  solution  of,  311 

Sodium  chloride,   standard  solution 
of,  237 

Sodium,  detection  of,  321 

Sodium  hydroxide,  action  of  oxalic 

acid  on,  245 

standard  solution  for  phosphorus, 
84 

Sodium  phosphate,  solution  of,  160 

Sodium  silicate,  formation  of,  72 

Sodium  thiosulphate,  standard  solu- 
tion of,  171 

Sodium  zinc  cyanide,  action  of  so- 
dium hydroxide  on,  245 

Solubility  of  precipitates,  20 

Solution  for  cleaning  glass,  35 

Solvents,  measuring  of,  19 


Split  shovel,  12 

"  Sprouting  "  of  the  button  in  assay- 
ing, 230 

Standardizing  solutions,  38 
Standardization    of    potassium    di- 

chromate  solution,  62 
Standard    potassium    permanganate 

solution,  51 
Standard  solution,  35 

definition  of,  36 
Standard  solution  of  iodine,  111 

of  potassium  dichromate,  62 
Standard  solutions,  correction  of,  39 

empirical,  37 

for  colorimetry,  43 

normal,  36 

Stannous  chloride,  oxidation  of,  by 
mercuric  chloride,  60 

reduction  of  iron  by,  60 

solution  of,  59 
Starch  solution,  111 
Static    electric    charges,    effects    in 

weighing,  119 

Steel,  carbon  in,  solution  and  com- 
bustion, 115 

copper  in,  150,  151 
Steel  drillings,  magnetized  wire  for 

transferring,  18 
Steel,  hydrogen  in,  153 

nitrogen  in,  151 

oxygen  in,  155 

solution  of,  for  total  carbon,  119 

solvents  for  carbon,  115 

sulphur  in,  oxidation  method,  108 

tungsten  in,  146 
Steiglitz,  J.,  indicators,  84 
Stillman,  water  analysis,  308 
Stirrer  operated  by  compressed  air, 

98 

Stoddard,  copper  by  electrolysis,  173 
Strontium,  detection  of,  321 


354 


INDEX 


Strontium,  determination  of,  300 
Sugar,  calorific  value  of,  266 

as  reducing  agent,  131 
Sulphide  ores,  assay  of,  232 
Sulphides,  action  of  iron  on,  228 

and  oxides,  reaction  between,  228 

oxidation  of,  by  nitrates,  227 
Sulphur,  forms  of,  in  iron,  104 
Sulphuric  acid  density  table,  333 

normal  solution  of,  36 
Sulphur  in  coal,  after  burning  in  a 
calorimeter,  263 

Eschka  method,  256 

rapid  method,  258 

Sulphur  in  iron,  American  Foundry- 
men's  Association  method,  110 

apparatus  for,  112,  114 
Sulphur  in  iron  or  steel,   evolution 
method,  111 

in  iron-slag,  159 

in  matte,  187 

in  ore,  73 

in  steel,  oxidation  method,  108 

oxidation  of,  with  sodium  nitrate, 
73 

precipitation    of    with     cadmium 

chloride,  113 
Sutton,  F.,  chromium,  290 

sodium  hydroxide  solution,  152 

zinc    by    potassium    ferrocyanide, 
178 

Table  for  sampling,  R.  H.  Richards, 

11 

Tannin,  solution  of,  175 
Tantalum,  detection  of,  321 

determination  of,  301 
Titanium  fluoride,  volatility  of,  71 
Tartaric  acid,  reagent,  220 
Telluride  ores,  assay  of,  234 
Tellurium  in  copper,  209 


Temperature  for  precipitating  phos- 
phorus, 78 

Template  for  sampling  anodes,  198 

Testing  of  cyanide  solutions,  243 

Testing  weights,  16 

Test  tubes  for  parting  gold  and  silver, 
232 

Test-tube  holder  for  the  water  bath, 
128 

Thallium,  detection  of,  321 
determination  of,  303 

Thorium,  detection  of,  321 
in  monazite,  304 

Thymol  for  titanium,  color  method, 
136 

Time  in  metallurgical  analysis,  im- 
portance of,  1 

Tin,  detection  of,  321 

determination  of,  294,  295,  296 

Tin  in  alloy,  213,  215 
in  bronze,  210 
in  copper,  220 

Titanium,  detection  of,  322 
color  method,  100 
determination  of  in  ore,  98 
in  iron,  135 

in  steel,  color  method,  136 
phosphorus    in   the    presence    of, 
86 

Titanium  sulphate,  reaction  of,  with 

sodium  acetate,  100 
standard  solution  of,  101 

"  Titrating  mixture  "  for  iron  deter- 
minations, 59 

Ton,  assay,  226 
avoirdupois,  226 
metric,  227 

Tongs,  crucible,  230 
cupel,  230 

1    scorifier,  235 

Total  cyanide,  244 


INDEX 


355 


Transferring  a  precipitate  to  a  cruci- 
ble, 27 

Treadwell-Hall,   formation  of  Prus- 
sian blue,  64 
mercury,  293 
tin,  295 
use  of  manganous  sulphate  in  the 

permanganate  method,  61 
vanadium,  297 
Trowel  for  sampling,  45 
Tube     for     determining     combined 

water,  49 

Tungsten,  detection  of,  322 
determination  of,  296 
in  steel,  146 

in  the  presence  of  chromium.  147 
Turbidimeter  method  for  sulphur  in 

coal,  258 
Turnbull's  blue,  64 

Uehling,  carbon  dioxide  meter,  283 
Ultimate  analysis  of  coal,  259 

calorific  power  from,  270 
United     States     Steel    Corporation 
method    of    sampling    iron-ore, 
46,  47,  48 

Uranium  acetate,  solution  of,  178 
Uranium,  detection  of,  322 

determination  of,  298 
Uranium  nitrate,  solution  of,  178 
Use  of  the  reductor,  58 

Vanadium,  chromium  and,  in  steel, 

141 

Vanadium,  detection  of,  322 
determination  of,  297 
in  steel,  144,  145 

Vaseline  and  paraffine  for  the  desic- 
cator, 30 

Vezin  sampler,  12 
Viscosity  of  lubricating  oil,  307 


Volatile  combustible  matter  in  coal, 

255 

Volatile  matter  in  coal,  254 
Volhard's  method  for  manganese  in 

ore,  88 

Vblumetric  analysis,  33 
Volumetric  apparatus,  33 

Walters  and  Apfelder,  antimony  in 

alloy,  218 
Walters'  method  for  manganese  in 

steel,  134 
Washing  precipitates,  26 

by  gravity,  26 
Washoe  method  for  silver  in  copper 

bullion,  200 

Watch  glasses  for  the  balance,  15 
Water    bath    for     dissolving    steel, 

128 
Water,  combined,  49 

hygroscopic,  49 

in  oil,  273 

permanent  hardness  of,  311 

softening  of,  312 

temporary  hardness  of,  311 
Water  value  of  calorimeter,  266 
Weighing,  15 
Weighing  bottle,  16 
Weighing  for  analysis,  18 
Weighing,  operation  of,  16 
Weighing  potash  bulb,  119,  121 
Weighing,  precautions  in,  18 

precipitates,  30 

temperature  for,  30 
Weight  book,  18 
Weight  box,  18 
Weight  of  ore  in  slime,  248 
Weights,  16 

testing,  16 

Weller's  color  method  for  titanium  in 
iron,  135 


356 


INDEX 


White,  A.  H.,  correction  in  calorim- 
etry,  265 

sampling  gas,  274 

sulphur  in  coal,  256 
White  alloys,  analysis  of,  213 
Williams,  gas  analysis,  281 
Winkler  and  Lunge,  gases,  275 

oxygen  absorbents,  276 
Working  table  for  the  laboratory,  3 
Works  laboratory,  plan  of,  6 

section  through,  7 
Wraith,  sampling  bullion,  197 

Yockey,  H.,  antimony  in  alloy,  218 
Yttrium,  detection  of,  322 


Yttrium,  determination  of,  305 

Zero-point  of  the  balance,  16 
Zimmerman-Reinhardt    method    for 

iron,  59 

Zinc  chloride  in  starch  solution,  112 
Zinc,  detection  of,  323 
Zinc  in  alloy,  212,  214,  217 

in  blast  furnace  slag,  191 

in  matte,  186 

in  ore,  178 

Zinc  oxide,  emulsion  of,  88,  135 
Zirconium,  detection  of,  323 

determination  of,  306 
Zwaluwenburg,  A.  Van,  sampling,  10 


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